Activity Chart Checks : (C4077) Elements input to activity that are not used internally

(C4077) Elements input to activity that are not used internally

Error In:
Completeness
Description:
There are elements that are input to an activity, but they are not used in its mini-spec.
Example:
In the figure, activity INST2 has the following mini-spec:

C/X=4;Y=2

D is shown as an input to activity INST2, but is not used within the mini-spec of INST2.
Erroneous Elements:
Events, conditions, and data-items