I was debugging an application somebody had created in framework X when I ran into a parameter I hadn't seen before so I wondered what it might do and what its legal values might be. I looked up the function in the manual. The entry for the function referred me to the separate manual for command line functions. I retrieved that manual and located the relevant chapter. It referred me to the man page for the function. I typed in man function and the man page referred me to the online help in the function. I typed function help and got the explanation that the parameter does, in fact, exist.
(Names redacted to protect me from the guilty, but their name ends with “pple”…)