Release 10.1A: OpenEdge Development:
AppBuilder

How AppBuilder runs XFTR event handlers

When a AppBuilder event occurs for a specific procedure file and the procedure file contains an XFTR code block with an XFTR event handler specified in the corresponding position, AppBuilder runs the XFTR event handler and passes it two parameters:

The context ID (integer) of the XFTR code block (INPUT parameter). A context ID is a unique integer ID for the code block. It can be used by other procedures in AppBuilder’s API.
The contents (CHARACTER) of the optional code section (the section in between the first and last comments) in the XFTR code block (INPUT-OUTPUT parameter).

Make sure that your XFTR event handler can accept these parameters.