DO supports a semi-automatic syllabification for ASCII, ST-Guide, Pure C Help and Manualpage. "Semi-automatic" means that you have to tell UDO at which position a word can be divided into two pieces.
You have two possibilities to set the syllabification patterns:
When converting to LaTeX the marks will be replaced by "\-". Then LaTeX knows that a word can be split at these positions.
When converting to RTF, Windows Help and HTML the marks are deleted.
If you want to display !- you have to use !/-.