This signal indicates that an attribute of an IEEE Std 1641 signal used in an operation originates from a parameter of the test that contains the operation. Refer to B.4 for an example. The data type and unit of the referenced parameter shall be identical to, or convertible to the data type and unit of the signal attribute. Note that this constraint is not enforced by the XML schema. Consumers should verify the constraint programmatically. Identifies the parameter. This signal indicates that an attribute of an IEEE Std 1641 signal used in an operation originates from the iterator of the Repeat operation that contains the parent operation of the current element. Refer to Annex B for an example. The data type and unit of the referenced iterator shall be identical to, or convertible to the data type and unit of the signal attribute. Note that this constraint is not enforced by the XML schema. Consumers should verify the constraint programmatically. Identifies the iterator.