Calamus is a desktop publishing application developed by invers Software, originally for Atari computers. It has a native CDK (for Calamus Document or Calamus Dokument) document format, and many other file formats.
Some or all CDK files begin with
"DMC CALAMUS" 0x00 ".CDK".
Calamus formats described in other articles:
- http://cd.textfiles.com/suzybatari2/new_file/extras/dtp/calamus/ → *.cdk