There is only one file type that uses the .KX extension:
KiXtart Tokenized Script File
A KX file is a tokenized version of the .KIX file written in the KiXtart scripting language. It is a script that is smaller and can be processed faster than KIX scripts. The file is encrypted and contains a signature for protection from any accidental changes in the script.
Since KIX files are saved in a text format that can be viewed and edited by a text editor, the KX file provides a higher level of security. KX tokenized scripts can be run from the KiXtart command line and by using the CALL command, unless the KX file is password protected.
Updated: August 25, 2016