No, that is entry 1346290 (升/ます). I'll add マス there.

@@ -24,0 +24,12 @@
+<sense>
+<pos>&n;</pos>
+<gloss>measure</gloss>
+</sense>
+<sense>
+<pos>&n;</pos>
+<gloss>square (e.g. of graph paper or Japanese manuscript paper)</gloss>
+</sense>
+<sense>
+<pos>&n;</pos>
+<gloss>box (e.g. on a form)</gloss>
+</sense>

I'm a bit uncomfortable about the "X" tag anyway, and I don't think it's appropriate here. Is there (still) an software that suppresses "X" entries.

personally, i don't think "masturbation", which is a perfectly inoffensive word (and the ~~preferred~~ term for the action), should qualify for an "X".  if "X" is to mean anything (and I'm not sure what really does keep it apart from "vulg"), I think it should be limited to terms for which the english glosses belong to a well-known list of bad words (e.g. http://en.wikipedia.org/wiki/Seven_dirty_words#The_words) rather than concepts that may make some people feel uncomfortable (e.g., someone else may complain that a certain sense of ホモ is not suitable for educational software.

@@ -22,1 +22,0 @@
-<misc>&X;</misc>

マス is a really common part of many words, and I don't think it's necessarily helpful to have this definition showing up all the time in educational software.

@@ -22,0 +22,1 @@
+<misc>&X;</misc>