How to search for empty custom date field via Zoho API?

How to search for empty custom date field via Zoho API?

Is it possible to search for an empty date field or do I have to set a default value and search for that?


I'm trying to create a search query via Zoho API among all Products. I would like to get only new Products having no value in a custom date field. I have been trying to search for NULL, empty and "doesn't contain|*20*" etc. without any luck.

http://crm.zoho.com/crm/private/json/Products/getSearchRecords?selectColumns=All&searchCondition=(My Date|is|NULL)&newFormat=2....

Is it possible to search for a combination of conditions?
like ...Status|is|Active ... AND ... My Date|<|2011-01-01 00:00:00...