Standalone Alpha vs. Varying Length Alpha Q

I am attempting to create a field that will contain concatenated
descriptions of several other 'flag' fields in a record format.  I have
defined the descriptions as constants (ElemDesc_xx, xx=flag identifier) in
the subproc (note: I also tried them as Standalone Alphas).  

I have a standalone alpha field (NotesField) large enough to accommodate all
descriptions, in case all flags are 'turned on'.  

I simply step through the flag fields, and if they are on, I add (NotesField
+= ElemDesc_xx) the description to the buffer.  I also optionally add a ', '
field, if at least one flag has been turned on subsequent to the current
flag.  

The above only seems to work if I use a variable length field as NotesField.
Otherwise, I get a compile error stating the operands are not compatible
with the operator.  I have no problem with the VARYING keyword, and I have
used it in this situation when we want to limit the output field to xxx
chars, but in this case, the maximum is within a reasonable length, so I
want to output the entire length.  

I can't seem to find anywhere in the documentation that states you can't use
the += on two fixed-length alpha fields.  Am I missing something, or is this
only possible with varying length fields? 


Tony Carolla
MedAmerica Billing Services, Inc.