When I first tried to edit vertex data in props I used # for commenting old values as in obj files with bad results, so I tried // for comments and it worked. Poser structure is similar to C with Begin End blocks { } and in C # is used for preprocessor instructions (#define #include etc). People use # for comments in Poser file, but I think that Poser doesn't accept it as comment and treats the line starting with # as a sintaxis error, and depending where you put this comment Poser ignores this error without any damage and in other places this error causes harm to the data. Probably in the places where you put # without any problem you can use any other strange symbol @ $ % & ?, etc with the same result, maybe a comment without # (only text) will work also at this place.

Stupidity also evolves!