You can break numlabel by strating a label with the single left quote character.

Code:
label define foo 42 "`single left quote"
label list foo
capture noisily numlabel foo , add
label drop foo
The single left quote causes problems in other places as well, .e.g. it will breaks levelsof when part of a string variable value.

This could probably be fixed but until then the single left quote is best avoided.

Best
Daniel
Last edited by daniel klein

http://www.statalist.org/forums/forum/general-stata-discussion/general/1328477-numlabel-_all-add-sometimes-return-mismatched-quotes