From Just Solve the File Format Problem
Common Ground from No Hands Software, allows any Windows or Mac program to create a document that can be viewed or printed by others even if they don't have the program that was used to create the document in the first place. Software comes with a document maker and a viewer. An early competitor to Adobe Acrobat, Common Ground was used to create portable, self-contained documentation applications, called "Digital Paper."
Common Ground version 1 files have Type
CGDC and Creator
Self Launching files have Type
APPL and Creator
Starting at byte 8 file header contains the string