\mathop is a TeX feature, and it has some subtlety in its implementation described in Documentation of \mathop.
Specifically, when the argument to \mathop is a single character, it should get centered vertically. Perhaps this could be implemented by tweaking buildHTML's groupTypes.mclass (when group.value.mclass === 'mop'), e.g. using the in-process \raisebox implementation (#685).
It's a minor bug, but comes up in defining custom symbols such as #657.
\mathopis a TeX feature, and it has some subtlety in its implementation described in Documentation of \mathop.Specifically, when the argument to
\mathopis a single character, it should get centered vertically. Perhaps this could be implemented by tweaking buildHTML'sgroupTypes.mclass(whengroup.value.mclass === 'mop'), e.g. using the in-process\raiseboximplementation (#685).It's a minor bug, but comes up in defining custom symbols such as #657.