Numerical Catagory Codes in XnViewMP

[AlanTC]

re Numerical Catagory Codes in XnViewMP:

Can you please direct me to some information about the three-digit Numerical Catagory Codes:
What they are used for?
How to use them?
How to apply them to existing jpg files?
How to apply them to new jpg files?

I have searched known XnViewMP instructions, XnViewMP Youtube files, and Forum but to no avail.

Cheers and thankyou,

AlanTC

[xnview]

you means category code in IPTC dialog?