MarkLogic 10 Product Documentation
cts.referenceNullable

cts.referenceNullable(
   reference as cts.reference
) as Boolean

Returns true() if the reference is nullable, false() otherwise.

Parameters
reference	An index reference.

cts.referenceNullable(cts.elementReference("TITLE",["nullable"]))
=>
true

MarkLogic 10 Product Documentationcts.referenceNullable