VarUtils.VAR CMP NULL
From RAD Studio VCL Reference
Description
VAR_CMP_NULL specifies that either one of the variants is nil, after a call to the function referenced by the VarCmp variable.
VAR_CMP_NULL is one of the possible return values of the function referenced by the VarCmp variable.
VAR_CMP_NULL specifies that either one of the variants is nil, after making the comparison.