> What is the difference in the source between SQLtype and
> SQLtype_ eg:
> SQL_SHORT and SQL_SHORT_

All sql types are defined twice, the even numbered definition refers
to a not-nullable value, the odd numbered definition is nullable.
So...

SQL_<type> = is an even number and represents a not nullable field

SQL_<type>_ = is an odd number and represents a nullable field.


HTH

Geoff Worboys
Telesis Computing