Why does my If Action block have vertical bars next to port names?

I inherited a model wherein every If Action block shows solid black bars along the edge of block outline, next to Inport and Outport names. It occurs even when I add a new Action block of my own.

Why?

Answer 1

[Guy Rouleau]

It is an optional display to let you know if the execution context of the conditionally executed subsystem can propagate outside or not. This page covers this topic: Conditional Execution Behavior

See Displaying Execution Context Bars at the bottom of this page to turn it on and off.