for those who are interested in:
I found this page:

Very simple code folding and syntax highlighting in Notepad++ for files created by the MIKE by DHI hydrodyanmic modelling software. Currently auto-detects files with .m21fm, .ecolab and .plc extensions. Requires Notepad++ (obviously).
Developed with MIKE by DHI 2012, but it should work for most versions of the software.

Bests Christian