REPORT Tag Express TEN.<entity type>

How do we express not equal to blank?

For Example:
{REPORT ORDER DETAILS:EC.Customer.Full Name.asc,O.ItemGroup,O.MenuItemName,O.PortionName,O.Quantity,O.ExactTotal:(ODI=True) && (TEN.Customers !='')}

This does not return any results.

EDIT:
Ok went the other way, al my {ENTITY NAME} contain a Zero (“0”) for any tickets with Customer Assigned:

{REPORT ORDER DETAILS:EC.Customer.Full Name.asc,O.ItemGroup,O.MenuItemName,O.PortionName,O.Quantity,O.ExactTotal:(ODI=True) && (TENC.Customers=0}

But it also does not work.

Thanks @emre - must be too tired! That works.

So please how can I use “not null” say for Customer Entity not assigned to a Ticket? At some stage in the future we may have no “0” in our Customer number to test?