[NTG-context] get measures as dimension in Lua

Hi, when I define a measure on the TeX side, I used to get at the value in Lua with tex.getdim, like: \definemeasure[Bleed][3mm] tex.getdimen("Bleed") But now I get "incorrect dimen name". I need it as a dimension, since I do calculations with other dimensions like "topspace". How should I do this correctly? (I just assume this used to work – the code is old any maybe stuck in an intermediate state where I switched from \newdim to \definemeasure…) Hraban