If you install the SDK from the Tools folder of CD2 of the Great Plains install discs, you will find the Report Writer Programmer's Interface document under Procedures and Functions.
This document contains the Report Writer functions I got added in GP v7.0, including RW_Left, RW_Right and RW_Substring.
As for creating a additional header on a calculated field, that is not possible. However, you could try using the additional header on the Document Number and suppressing it when the righthand 14 characters have not changed.
To suppress it you could create a calculated conditional field which compares the current value to the last occurrence and setting the returned value to 1 or 0 accordingly.
David Musgrave [MSFT]
Senior Development Consultant
Escalation Engineer
MBS Support - Asia Pacific
Microsoft Business Solutions
Any views contained within are my personal views and
not necessarily Microsoft Business Solutions policy.
This posting is provided "AS IS" with no warranties,
and confers no rights.