Using "IN" or "OR" statement in SSRS

I would like to assign a value 1 to my expression if workflowcode is DRCP OR DRCOCP and TemporaryPermanent is 0

Is this expression valid?

=Sum(iif(Fields!WorkflowCode.Value = "DRCP"   And Fields!TemporaryPermanent.Value = 0, 1, 0)) OR
 Sum(iif(Fields!WorkflowCode.Value = "DRCOCP" And Fields!TemporaryPermanent.Value = 0, 1, 0))

OR

Is this expression valid?

=Sum(iif(Fields!WorkflowCode.Value = "DRCP" OR "DRCOCP" And Fields!TemporaryPermanent.Value = 0, 1, 0))

Thank you in advance!