[Dev-luatex] user_defined whatsits

[Patrick Gundlach]

Hi,

once in a while I find surprises in the luatex reference manual, such as the user_defined whatsits (great!).

1) Is the user_id field completely up to me? So I can use it somewhat as an attribute?
2) Will the user_defined whatsit stay in LuaTeX (I know, nothing is fixed, but the developers might have a tendency)
3) am I dreaming or is this really real?

Patrick