Undocumented

Undocumented could simply mean that a known feature was not documented. In Director circles it's more usually referring to an unofficial feature in Director that works perfectly well, but that did not get full testing prior to that release. Some cases are semi-official, in that the feature was intended to be finished but didn't quite make it. Other cases are unofficial, where the engineer who put the feature into the program didn't necessarily run the idea by the management.

A key step in the life of an undocumented feature is figuring out that it exists. Sometimes it's possible to guess a feature, by trying different property names that you think might work. More often the feature isn't one that could easily be guessed, and may require alcohol induced confessions from the engineers themselves. Torture has also been known to work.

A useful advantage of leaking the details of an undocumented feature is that it will get some good testing by people who are interested in it, and this will increase the chances of it being officially supported in a later release. One very good example was GetPixel() and SetPixel(), which worked quite well in Director 7, and ultimately helped lead to the creation of Imaging Lingo in Director 8.