Tagging music

Yeah, how the fuck do you tag this things? I have a little problem and I get rid of it
(Demo Version) or (Demo)
(Extended Version) or (Extended)
.feat Featuring featuring feat
Pt. 1 Part 1 Part I
etc....give examples and what you create it's right.

Personally I use
(Demo)
(Extended)
.feat

and then it depends on the band.
Any normal band is just Part 1, but some bands it just feels better using Pt. I

What is on the back cover or official source is what goes verbatim in the tags, including misspelling and non-standard capitalization, no exceptions.