X11: How does “the” clipboard work? ( via ) is a technical walk through the modern X11 selection system , one that winds up discussing things at the level of the X protocol and Xlib, with helpful code examples. I learned some quite useful things in the process, for example how to use xclip to query things to find out what formats a selection is available in.

(Technical details about X selections are relevant to me because I use a program that deals with them and which I'd like to see do so more conveniently.)