diff --git a/Tests/mtiLib/data/mti/gsubligature.ttx.GSUB b/Tests/mtiLib/data/mti/gsubligature.ttx.GSUB
index ad8f50542..26c88c81c 100644
--- a/Tests/mtiLib/data/mti/gsubligature.ttx.GSUB
+++ b/Tests/mtiLib/data/mti/gsubligature.ttx.GSUB
@@ -7,7 +7,7 @@
       <LookupType value="4"/>
       <LookupFlag value="0"/>
       <!-- SubTableCount=1 -->
-      <LigatureSubst index="0" Format="1">
+      <LigatureSubst index="0">
         <LigatureSet glyph="I">
           <Ligature components="J" glyph="IJ"/>
         </LigatureSet>
diff --git a/Tests/otlLib/data/gsub_51.ttx b/Tests/otlLib/data/gsub_51.ttx
index ed972ca26..86f0f66bd 100644
--- a/Tests/otlLib/data/gsub_51.ttx
+++ b/Tests/otlLib/data/gsub_51.ttx
@@ -97,7 +97,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -107,7 +107,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/otlLib/data/gsub_52.ttx b/Tests/otlLib/data/gsub_52.ttx
index c9e4a88ca..6b26e7877 100644
--- a/Tests/otlLib/data/gsub_52.ttx
+++ b/Tests/otlLib/data/gsub_52.ttx
@@ -97,7 +97,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -107,7 +107,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/subset/data/Lobster.subset.ttx b/Tests/subset/data/Lobster.subset.ttx
index eef803a1d..8089b246a 100644
--- a/Tests/subset/data/Lobster.subset.ttx
+++ b/Tests/subset/data/Lobster.subset.ttx
@@ -625,7 +625,7 @@ This license is available with a FAQ at: http://scripts.sil.org/OFL
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="I">
             <Ligature components="J" glyph="IJ"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gpos5_font1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gpos5_font1.ttx.GSUB
index 88d3f2437..f81552a84 100644
--- a/Tests/ttLib/tables/data/aots/gpos5_font1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gpos5_font1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g30">
             <Ligature components="g31" glyph="g18"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub4_1_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub4_1_lookupflag_f1.ttx.GSUB
index f485610c8..7dc3472e4 100644
--- a/Tests/ttLib/tables/data/aots/gsub4_1_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub4_1_lookupflag_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="2"/><!-- ignoreBaseGlyphs -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f1.ttx.GSUB
index 9466f916a..e9eb9eab6 100644
--- a/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
             <Ligature components="g19" glyph="g24"/>
diff --git a/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f2.ttx.GSUB
index bc25e8406..6756dfd1e 100644
--- a/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligatures_f2.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19" glyph="g24"/>
             <Ligature components="g19,g20" glyph="g23"/>
diff --git a/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligsets_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligsets_f1.ttx.GSUB
index 0ea6495c2..ab043680b 100644
--- a/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligsets_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub4_1_multiple_ligsets_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub4_1_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub4_1_simple_f1.ttx.GSUB
index ecc8fa684..7f3012aa4 100644
--- a/Tests/ttLib/tables/data/aots/gsub4_1_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub4_1_simple_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f1.ttx.GSUB
index 43cecb708..ee74866be 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f2.ttx.GSUB
index 57f38618a..3b6e0cb83 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f3.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f3.ttx.GSUB
index b3eae742e..92069ec5b 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f3.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f3.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f4.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f4.ttx.GSUB
index 252f4fd6d..69409f471 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f4.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_boundary_f4.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_lookupflag_f1.ttx.GSUB
index 5200b8f7f..e9cf696c9 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_lookupflag_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f1.ttx.GSUB
index 900cffe06..f6a979307 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f2.ttx.GSUB
index 92b5a6ffd..1865fc8b8 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_multiple_subrules_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_next_glyph_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_next_glyph_f1.ttx.GSUB
index ce08238f1..73eb6396c 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_next_glyph_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_next_glyph_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f1.ttx.GSUB
index 15e12a916..1fa4e823c 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f2.ttx.GSUB
index d2d2b411b..c482c26c0 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_simple_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining1_successive_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining1_successive_f1.ttx.GSUB
index 0d4e54685..5dba25448 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining1_successive_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining1_successive_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f1.ttx.GSUB
index e2e11641c..020fb1efe 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f2.ttx.GSUB
index 62baded7a..9217e0910 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f3.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f3.ttx.GSUB
index e6e3e6926..fa3b04bd7 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f3.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f3.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f4.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f4.ttx.GSUB
index 61b74b906..7ebeb58c5 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f4.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_boundary_f4.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_lookupflag_f1.ttx.GSUB
index 0b4f1f4df..aefb46cb9 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_lookupflag_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f1.ttx.GSUB
index d7b15577c..969c91d2f 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f2.ttx.GSUB
index 20e814f7c..f265ed148 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_multiple_subrules_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_next_glyph_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_next_glyph_f1.ttx.GSUB
index 450e361f4..322f89154 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_next_glyph_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_next_glyph_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f1.ttx.GSUB
index ab9866b86..bec940175 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f2.ttx.GSUB
index 2240e677a..21e389424 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_simple_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining2_successive_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining2_successive_f1.ttx.GSUB
index cc752d3ca..b4c1d4f74 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining2_successive_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining2_successive_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f1.ttx.GSUB
index e1d2e8e27..8aac90344 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f2.ttx.GSUB
index 6b1569486..5ddafa255 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f3.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f3.ttx.GSUB
index 5b4bd2e95..5c0265c04 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f3.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f3.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f4.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f4.ttx.GSUB
index 68dc24183..e52ca51f2 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f4.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_boundary_f4.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_lookupflag_f1.ttx.GSUB
index d5f917905..b83190980 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_lookupflag_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_next_glyph_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_next_glyph_f1.ttx.GSUB
index 6e9ba2bf9..8801bed33 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_next_glyph_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_next_glyph_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f1.ttx.GSUB
index 900aaf4dd..9b8f7e156 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f2.ttx.GSUB
index b38c84558..f568a3807 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_simple_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_chaining3_successive_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_chaining3_successive_f1.ttx.GSUB
index eadc29de0..68d5abae7 100644
--- a/Tests/ttLib/tables/data/aots/gsub_chaining3_successive_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_chaining3_successive_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f1.ttx.GSUB
index a04cb99e3..94df4e8af 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f2.ttx.GSUB
index 027564300..58191c167 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_boundary_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_expansion_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_expansion_f1.ttx.GSUB
index a694e57f2..95d7c6d49 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_expansion_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_expansion_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f1.ttx.GSUB
index 527bfe9f0..3ade9e951 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f2.ttx.GSUB
index a80ff1f90..efb4aeb8e 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_lookupflag_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f1.ttx.GSUB
index 901530f40..f441d4d99 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f2.ttx.GSUB
index acd59971a..9cb0fbf71 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_multiple_subrules_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_next_glyph_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_next_glyph_f1.ttx.GSUB
index 055a21fd1..238cc6c18 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_next_glyph_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_next_glyph_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_simple_f1.ttx.GSUB
index db5f74cac..cb4bc4fdb 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_simple_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_simple_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_simple_f2.ttx.GSUB
index a775e8fa2..b31eae8ff 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_simple_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_simple_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context1_successive_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context1_successive_f1.ttx.GSUB
index 113187d2a..63dcdc545 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context1_successive_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context1_successive_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f1.ttx.GSUB
index 1bd285872..76bf0cb4b 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f2.ttx.GSUB
index e78feec15..a963b3da8 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_boundary_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_classes_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_classes_f1.ttx.GSUB
index 27fc2598e..463f1c053 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_classes_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_classes_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_classes_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_classes_f2.ttx.GSUB
index 3e7e2cd4c..20b643dbe 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_classes_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_classes_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_expansion_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_expansion_f1.ttx.GSUB
index 5536c1d0a..d64741952 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_expansion_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_expansion_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f1.ttx.GSUB
index 8f90344ed..19da246a6 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f2.ttx.GSUB
index b2a83cdc5..0d5a49c9d 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_lookupflag_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f1.ttx.GSUB
index ac2366a94..4bd99cb18 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f2.ttx.GSUB
index fe63a850e..43052de0c 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_multiple_subrules_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_next_glyph_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_next_glyph_f1.ttx.GSUB
index a22a91c54..fdbea86af 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_next_glyph_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_next_glyph_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_simple_f1.ttx.GSUB
index 15a4b6c89..3c3b0b43f 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_simple_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_simple_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_simple_f2.ttx.GSUB
index 7282e4396..03c2d7790 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_simple_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_simple_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context2_successive_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context2_successive_f1.ttx.GSUB
index 2c9c1b5bd..3346c15ce 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context2_successive_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context2_successive_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f1.ttx.GSUB
index e5b210764..066e63530 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f2.ttx.GSUB
index 4e2a93fbf..bea7f48a7 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_boundary_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f1.ttx.GSUB
index 5c232508d..7917f83a0 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f2.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f2.ttx.GSUB
index 49b508bc7..ed9352e7a 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f2.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_lookupflag_f2.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_next_glyph_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_next_glyph_f1.ttx.GSUB
index 6930031ef..33e50d06a 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_next_glyph_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_next_glyph_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_simple_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_simple_f1.ttx.GSUB
index 51a2d7f67..53f97c70b 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_simple_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_simple_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/gsub_context3_successive_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/gsub_context3_successive_f1.ttx.GSUB
index 80c89fb01..f73628502 100644
--- a/Tests/ttLib/tables/data/aots/gsub_context3_successive_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/gsub_context3_successive_f1.ttx.GSUB
@@ -50,7 +50,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
@@ -60,7 +60,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g21">
             <Ligature components="g22" glyph="g61"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/lookupflag_ignore_attach_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/lookupflag_ignore_attach_f1.ttx.GSUB
index 874ba00b2..42876ead7 100644
--- a/Tests/ttLib/tables/data/aots/lookupflag_ignore_attach_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/lookupflag_ignore_attach_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="512"/><!-- markAttachmentType[2] -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g11">
             <Ligature components="g13,g26" glyph="g15"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/lookupflag_ignore_base_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/lookupflag_ignore_base_f1.ttx.GSUB
index f485610c8..7dc3472e4 100644
--- a/Tests/ttLib/tables/data/aots/lookupflag_ignore_base_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/lookupflag_ignore_base_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="2"/><!-- ignoreBaseGlyphs -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/lookupflag_ignore_combination_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/lookupflag_ignore_combination_f1.ttx.GSUB
index e257bd76c..ffdc2aeae 100644
--- a/Tests/ttLib/tables/data/aots/lookupflag_ignore_combination_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/lookupflag_ignore_combination_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="514"/><!-- ignoreBaseGlyphs markAttachmentType[2] -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/lookupflag_ignore_ligatures_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/lookupflag_ignore_ligatures_f1.ttx.GSUB
index d270f3c62..db7fcc0c0 100644
--- a/Tests/ttLib/tables/data/aots/lookupflag_ignore_ligatures_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/lookupflag_ignore_ligatures_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="4"/><!-- ignoreLigatures -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/ttLib/tables/data/aots/lookupflag_ignore_marks_f1.ttx.GSUB b/Tests/ttLib/tables/data/aots/lookupflag_ignore_marks_f1.ttx.GSUB
index 3712c0669..b3fd500a1 100644
--- a/Tests/ttLib/tables/data/aots/lookupflag_ignore_marks_f1.ttx.GSUB
+++ b/Tests/ttLib/tables/data/aots/lookupflag_ignore_marks_f1.ttx.GSUB
@@ -33,7 +33,7 @@
         <LookupType value="4"/>
         <LookupFlag value="8"/><!-- ignoreMarks -->
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="g18">
             <Ligature components="g19,g20" glyph="g23"/>
           </LigatureSet>
diff --git a/Tests/varLib/data/master_ttx_interpolatable_otf/TestFamily2-Master0.ttx b/Tests/varLib/data/master_ttx_interpolatable_otf/TestFamily2-Master0.ttx
index fa22b7da4..c83f2346e 100644
--- a/Tests/varLib/data/master_ttx_interpolatable_otf/TestFamily2-Master0.ttx
+++ b/Tests/varLib/data/master_ttx_interpolatable_otf/TestFamily2-Master0.ttx
@@ -801,7 +801,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="f">
             <Ligature components="t" glyph="f_t"/>
           </LigatureSet>
diff --git a/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Bold.ttx b/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Bold.ttx
index 6974f3158..cf4b5dae6 100644
--- a/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Bold.ttx
+++ b/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Bold.ttx
@@ -407,7 +407,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="a">
             <Ligature components="e,s,s" glyph="s"/>
           </LigatureSet>
diff --git a/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Regular.ttx b/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Regular.ttx
index 4487a1605..c93da2a8f 100644
--- a/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Regular.ttx
+++ b/Tests/varLib/data/master_ttx_interpolatable_ttf/SparseMasters-Regular.ttx
@@ -407,7 +407,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="a">
             <Ligature components="e,s,s" glyph="s"/>
           </LigatureSet>
diff --git a/Tests/varLib/data/master_ttx_interpolatable_ttf/TestFamily2-Master0.ttx b/Tests/varLib/data/master_ttx_interpolatable_ttf/TestFamily2-Master0.ttx
index b3a46355a..20c9cb052 100644
--- a/Tests/varLib/data/master_ttx_interpolatable_ttf/TestFamily2-Master0.ttx
+++ b/Tests/varLib/data/master_ttx_interpolatable_ttf/TestFamily2-Master0.ttx
@@ -1116,7 +1116,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="f">
             <Ligature components="t" glyph="f_t"/>
           </LigatureSet>
diff --git a/Tests/varLib/data/test_results/InterpolateLayout.ttx b/Tests/varLib/data/test_results/InterpolateLayout.ttx
index 31668b49f..512b97037 100644
--- a/Tests/varLib/data/test_results/InterpolateLayout.ttx
+++ b/Tests/varLib/data/test_results/InterpolateLayout.ttx
@@ -128,7 +128,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="f">
             <Ligature components="t" glyph="f_t"/>
           </LigatureSet>
diff --git a/Tests/varLib/data/test_results/SparseMasters.ttx b/Tests/varLib/data/test_results/SparseMasters.ttx
index 63e4c0ea8..a3f8e619d 100644
--- a/Tests/varLib/data/test_results/SparseMasters.ttx
+++ b/Tests/varLib/data/test_results/SparseMasters.ttx
@@ -425,7 +425,7 @@
         <LookupType value="4"/>
         <LookupFlag value="0"/>
         <!-- SubTableCount=1 -->
-        <LigatureSubst index="0" Format="1">
+        <LigatureSubst index="0">
           <LigatureSet glyph="a">
             <Ligature components="e,s,s" glyph="s"/>
           </LigatureSet>