[CPN] Revision of proposed changes in Art. 21

[David Marjanovic]

...Sorry. Version 3 makes very clear that gender agreement is optional. 
But I want number agreement to be optional, too:

> But the statement in the draft  implies that agreement IS optional! It
 > says "may be changed," not "must be changed"!

The "should not be changed" part is in a Note, not a Recommendation. 
That may send mixed messages. ...But it's a Note _to_ a Recommendation. Hm.

...Actually, I can live with that. I guess the two long Examples to Rec. 
21A threw me off, and I forgot where I was.