--- a/sqlite3tcsq.tcl
+++ b/sqlite3tcsq.tcl
@@ -100,8 +100,13 @@
     return [$hdl changes]
 }
 
-# Retrieve auto_increment value for the last insert. 
-# Don't know how portable this, probably not much. Works with MySQL
+# Retrieve auto_increment value for the last insert.  This is used
+# because sqlscreens normally expects the integer primary key to
+# autoincrement, and does not set the value. For this to work with
+# sqlite3, the column must be declared "INTEGER PRIMARY KEY" (exactly,
+# INT PRIMARY KEY or int(11) PRIMARY KEY do not work). In declared
+# appropriately, the column becomes an alias for the SQLite ROWID
+# column: http://www.sqlite.org/lang_createtable.html#rowid
 proc SQLITE3insertid {hdl} {
     return $hdl last_insert_rowid
 }