Hi, In the following minimal example \startformula P = \left(\vphantom{\sum}\smash{\sum_{\startsubstack 1 \le i \le p \NR 1 \le j \le q \NR 1 \le k \le r \NR \stopsubstack}} a_{ij}b_{jk}c_{ki} \right) \stopformula \smash does not work properly in mkiv – in mkii it runs just fine! Best regards, Dominik