Proper value of $TERM for screen running in an xterm-256color terminal

[Dun Peal]

I'm wondering what the proper value of $TERM would be for screen
running in a terminal which initially has its $TERM variable equal to
"xterm-256color". Once I launch screen, $TERM becomes "screen", which
seems to lack many capabilities, notably: applications don't consider
it to be capable of displaying 256 colors.

Searching the web brought up several potential values that $TERM
should have in this situation, including "screen-256color" and
"screen.xterm-256color", but I'm not sure what's the proper answer.