SUBSTRING Function - via a tempory table?

Hi all, happy new year.

I'm trying to perform the following:

For a G/L Entry, if its G/L Account No. contains the substring 'DUM' to set a flag field accordingly. I realise that Navision doesn't have a concept of a SUBSTRING function, and frustratingly the 'DUM' sequence is not in the same place everytime (i.e. its not always the 1st three characters).

What I have done is (GLEntryTemp is defined as being a 'Tempory' variable):

GLEntryTemp.COPY("G/L Entry");
  
  GLEntryTemp.RESET;
  GLEntryTemp.SETFILTER("G/L Account No.",'%1','*DUM*');

  //IF (GLEntryTemp.COUNT > 0) THEN tempFS := 'D';                     //Account No.s containing 'DUM'....

  //IF GLEntryTemp.FIND('-') THEN tempFS := 'D';

  IF NOT(GLEntryTemp.ISEMPTY) THEN tempFS := 'D';
END;

This works so far as copying the record to the temporary store, and no further....

The two commented-out lines represent alternative ways that I have tried to get it working (no luck!).

SO the question is what I'm trying to do, do-able, or do I need to approach the problem differently?


Thanks for any advice!