Dear All, Following the instructions in tagging.pdf, I tried \setupbackend[format=pdf/ua-2] \setuptagging[state=start] \enabledirectives [backend.usetags=crap] \registermathsymbol[default][en][ z ][the variable] \registermathsymbol[default][en][ k ][the index] \starttext \startformula \startalign \NC \left|(z_0+h)^n - z_0^n\right| \NC = \left|\sum_{k=1}^n \binom{n}{k}h^k z_0^{n-k}\right| \NR \NC \NC = \left |h \sum_{k=0}^{n-1} \binom{n}{k+1} h^k z_0^{n-1-k}\right| \NR \NC \NC = \left|h \sum_{k=0}^{n-1} \frac n {k+1} \binom{n-1}{k} h^k z_0^{n-1-k}\right| \NR \NC \NC \le n | h| \sum_{k=0}^{n-1} \binom{n-1}{k} |h|^k |z_0|^{n-1-k} \NR \NC \NC \le n | h| (|z_0|+|h|)^{n-1} \NR \stopalign \stopformula \stoptext This creates within the pdf the XML attachment below: This XML contains all the information from the formula. Wrapping it into \usemodule[mathml] \starttext \xmlprocessdata{}{ % content of XML file }{} \stoptext produces which is also what my Mac screen reads from the original PDF, but it is evidently not what I want. Does someone have a working example that shows how to do this right? Thanks, Matthias