Hi, I read the document "Using \startalign and friends" of Aditya (that it's good) and I can't find anything under ams aligned. Is this an equivalent in ConText? For example, what is the equivalent of: \begin{equation*} \left.\begin{aligned} & 2^2 | n_0\\ & 4^2 | n_0 + 2 \Rightarrow (2^2)^2 | n_0 +2 \Rightarrow 2^2 | n_0 +2 \text{ ya que } 2^2 | (2^2)^2 \end{aligned}\right\} \Rightarrow 2^2 | (n_0 + 2 - n_0) \Rightarrow 2^2 | 2 \end{equation*} in ConTeXt? I tried something like: \startformula \startmathalignment \NC \startaligned \NC \lambda_{0, \lvert k - s \rvert} (n) \NC < f(n) \NR \NC \text{ per a $n$ suficientment gran } \NC \NR \stopaligned \NC \iff \startaligned \NC \lambda_{s, k} (n) \NC < f(n) \NR \NC \text{ per a $n$ suficientment gran } \NC \NR \stopaligned \NR[+] \NC \lambda_{s, k} (n) < f(n) \text{ per a $n$ suficientment gran } \NC \iff \lambda_{0, \lvert k - s \rvert} (n) < f(n) + C \text{ per a $n$ suficientment gran } \NR[+] \stopmathalignment \stopformula but " Undefined control sequence" appears to me. Thanks a lot, Xan. PS: Please CCme