It'd be useful to see a table showing the commonality of these commands -- POSIX standard, GNU Coreutils, X/Open, Linux Standard Base, or whatever non-standard

It'd be useful to see a table showing the commonality of these commands -- POSIX standard, GNU Coreutils, X/Open, Linux Standard Base, or whatever non-standard package they come from. As it is, it's next to useless for anyone who isn't plugged into the author's own desktop.