Document or remove [iget] entry method attribute

[epmikida]

It is listed as a reserved word in the manual, but has no other documentation. It is in the code base as well, but it's not clear if it is a feature we want to keep.

[stwhite91]

I think it doesn't hurt much to keep it. The code appears to be pretty well self-contained, and it's potentially useful. Still need to document it though