diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 4c63bd4dc6..9b506471fe 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -630,7 +630,7 @@ TupleDescInitEntry(TupleDesc desc,
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
-	/* attacl, attoptions and attfdwoptions are not present in tupledescs */
+	/* variable-length fields are not present in tupledescs */
 
 	tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(oidtypeid));
 	if (!HeapTupleIsValid(tuple))
@@ -691,7 +691,7 @@ TupleDescInitBuiltinEntry(TupleDesc desc,
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
-	/* attacl, attoptions and attfdwoptions are not present in tupledescs */
+	/* variable-length fields are not present in tupledescs */
 
 	att->atttypid = oidtypeid;
 
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 81cc39fb70..8bbf23e452 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -723,9 +723,10 @@ CheckAttributeType(const char *attname,
  *		Construct and insert a set of tuples in pg_attribute.
  *
  * Caller has already opened and locked pg_attribute.  tupdesc contains the
- * attributes to insert.  attcacheoff is always initialized to -1, attacl,
- * attfdwoptions and attmissingval are always initialized to NULL.  attoptions
- * must contain the same number of elements as tupdesc, or be NULL.
+ * attributes to insert.  attcacheoff is always initialized to -1.  attoptions
+ * supplies the values for the attoptions fields and must contain the same
+ * number of elements as tupdesc or be NULL.  The other variable-length fields
+ * of pg_attribute are always initialized to null values.
  *
  * indstate is the index state for CatalogTupleInsertWithInfo.  It can be
  * passed as NULL, in which case we'll fetch the necessary info.  (Don't do
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 5e9cae26a0..c35f09998c 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6734,7 +6734,10 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 					   list_make1_oid(rel->rd_rel->reltype),
 					   0);
 
-	/* construct new attribute's pg_attribute entry */
+	/*
+	 * Construct new attribute's pg_attribute entry.  (Variable-length fields
+	 * are handled by InsertPgAttributeTuples().)
+	 */
 	attribute.attrelid = myrelid;
 	namestrcpy(&(attribute.attname), colDef->colname);
 	attribute.atttypid = typeOid;
@@ -6758,8 +6761,6 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attinhcount = colDef->inhcount;
 	attribute.attcollation = collOid;
 
-	/* attribute.attacl is handled by InsertPgAttributeTuples() */
-
 	ReleaseSysCache(typeTuple);
 
 	tupdesc = CreateTupleDesc(lengthof(aattr), (FormData_pg_attribute **) &aattr);