Method parameter - optional but not nullable

Hi,

In Contacts Manager API spec, parameter "option" of find() is optional but not nullable:
http://www.w3.org/2012/sysapps/contacts-manager-api/#widl-ContactsManager-find-Promise-ContactFindOptions-options 

What does that mean? Is there any difference between optional and nullable?

Thanks in advance.

Regards,
Deqing

Received on Wednesday, 18 December 2013 10:03:56 UTC