There is only one file type that uses the .VOK extension:
PocketVok Vocabulary File
List of words recognized by PocketVok, a PDA-based vocabulary training program for Pocket PC; used for learning words and building a vocabulary as well as learning foreign words, countries and their capitals, etc.
VOK files are also recognized by WinVok, the Windows version of PocketVok.
Updated: February 2, 2008