Activity Chart Checks : (C4075) Elements output from activity that are not affected internally

(C4075) Elements output from activity that are not affected internally

Error In:
Completeness
Description:
There are elements that are output of an activity, but they are not affected (modified or generated) in its mini-spec.
Example:
In the figure, activity INST2 has the following mini-spec:
C and D/Y=2
X is shown as an output from activity INST2, but is not affected within the mini-spec of INST2.
Erroneous Elements:
Events, conditions, and data-items