src/include/access/tupconvert.h

@@ -16,6 +16,8 @@
 
 #include "access/htup.h"
 
+/*Conversion of tuple types to other types.*/
+
 typedef struct TupleConversionMap {
     TupleDesc indesc;    /* tupdesc for source rowtype */
     TupleDesc outdesc;   /* tupdesc for result rowtype */