KTimeTracker user defined fieldsin ics file

In reference to BUG: 352441

I am considering adding user defined fields to events (and maybe tasks) in KTimeTracker.

I need to know interoperability considerations with other PIM programs.

Using the same ics file with Merkuro, I realised that KTimeTracker removes the “DESCRIPTION” entry added by Merkuro, if I save the file (though Merkuro doesn’t seem to lose extra stuff like that).

Then I have seen the extended fields as added by KTimeTracker being of the form X-KDE-variablename. e.g. X-KDE-ktimetracker-duration.
Should I be using KDE as the namespace for user added fields, or should I go with X-<username>-variablename or X-USERCUSTOM-variablename?