Added comments for clarity

bats/triggers.bats

@@ -156,6 +156,7 @@ SQL
 
 @test "triggers: Upgrade dolt_schemas" {
     rm -rf .dolt
+    # old_dolt_schemas was created using v0.19.1, which is pre-id change
     cp -a $BATS_TEST_DIRNAME/helper/old_dolt_schemas/. ./.dolt/
     run dolt sql -q "SELECT * FROM dolt_schemas" -r=csv
     [ "$status" -eq "0" ]

go/libraries/doltcore/doltdb/system_table.go

@@ -220,6 +220,11 @@ const (
 // Tags for dolt_schemas table
 // for info on unaligned constant: https://github.com/dolthub/dolt/pull/663
 const (
+	// Old tag numbers for reference
+	//DoltSchemasTypeTag = iota + SystemTableReservedMin + uint64(4003)
+	//DoltSchemasNameTag
+	//DoltSchemasFragmentTag
+
 	DoltSchemasIdTag = iota + SystemTableReservedMin + uint64(4007)
 	DoltSchemasTypeTag
 	DoltSchemasNameTag