NIL responses/responses would also be appreciated.

15:04 Dec 5, 2011 

To me, "NIL responses ... would also be appreciated" means "please do respond, even if the answer is no, none, not applicable, etc.", as here, e.g.:
Please respond (even if your response is negative/nil) to:
http://www.school-portal.co.uk/GroupDownloadFile.asp?GroupId...

Depending on the context (and you MUST have some, unless you have been asked to translate these 7 words in complete isolation), this could be, e.g. so that they know you have read the question and not missed it by accident (in the case of a survey or form), or so that they can cross you off the list of attendees (in the case of an invitation, etc).

I am not sure how you should deal with this in French. Perhaps something with "réponse néant" or "mention s/o (sans objet)", e.g.:

c.Responding to the Issues Management Analyst and advising whether or not the BD is applicable to their division (if not applicable to their division, reply with a “nil” response).
c.Répondre à l’analyste de la gestion des cas et indiquer si le DI s’applique ou non à sa division (si non, répondre S/O).
http://www.tc.gc.ca/fra/aviationcivile/opssvs/servicesdegest...