Hi Hans, I have a long document which typesets correctly with mkiv, but I get a (cryptic for me…) fatal error message when I try to typeset it in lmtx: ! error: (nodes): trying to delete an attribute reference of a non attribute list node 4476mtx-context | fatal error: return code: 256 I could finally find the origin of the error, which is exposed in the following example: if you comment out the part from \startformula ... \stopformula, the file typesets correctly. But with this part, one gets the above error message, the culprit being \liminfbar which is defined in the first line. Note that \liminfbar is accepted when it is inline math. Best regards: OK %%% begin bug-math-lmtx.tex \definemathcommand[liminfbar][limop] {\underline{\mfunctionlabeltext{lim}}} \starttext If $(u_{n})_{n}$ is a sequence of real numbers, we define its {\it limit inferior}, denoted $\liminfbar$ by setting: \startformula a_{n} := \inf\{u_{k} \; ; \; k \geq n \}, \qquad\text{and then}\quad \liminfbar_{n\to\infty} u_{n} := \sup_{n \geq 1} a_{n}. \stopformula \stoptext %%% end bug-math-lmtx.tex