Has Requirements is a reference field for automated tests, scripts and requirements. It is "True" when a script or requirement is associated with one or more requirements (directly or indirectly).
To find all requirements and scripts associated to requirements (directly or indirectly):
HasRequirements = True
To find all automated tests that have associated requirements of type 'QTP':
HasRequirements = Yes AND Type = 'QTP' AND EntityType = Test
=, !=, IS, IS NOT