Activity Chart Checks : (C3039) Flow-lines between external activities

(C3039) Flow-lines between external activities

Error In:
Correctness
Description:
There are compound flow-lines between external activities. These flow-lines, even if they exist, should not be specified in the chart where the source and target activities are external, and therefore out of the description scope.
Example:
In the following figure, data-item A is shown flowing between external activities INPUT_1 and INPUT_2.
Erroneous Elements:

Components of the erroneous flow-lines