When assigning specific line attributes to fields or text in a DEF_BREAK command note that the line numbers used are "offsets" from the start of the print line. Thus specifying *L001 against a field does not mean the field will actually print on line 1 of the report. The field will print on line 1 of the "group" of fields that make up the DEF_BREAK command.
If you use an expandable group expression in a DEF_BREAK command FIELDS and/or TRIGGER_BY parameter(s) and you change the layout using the report design facility, LANSA will substitute the expression with the actual fields. This is the only way LANSA can assign attributes to the individual fields regardless of the group they initially came from.
Note that trailing breaks really do "trail behind" the data being processed by the function. For example, when a trailing break definition like this is "triggered" for printing:
DEF_BREAK NAME(#REGTOT) FIELDS(#REGION #REGVAL) TRIGGER_BY(#REGION)
it does not really print the current content of fields #REGION and #REGVAL. It actually prints the contents of 2 "internal" fields that contain the "previous" #REGION value and the "previous" #REGVAL value. This feature is what makes the processing of "break" totalling so simple and quick within LANSA.