Set coupler masks feature

[jjanmarine3]

Hi guys, can someone pse explain to me what the purpose is of the 'set coupler masks' feature when editing a session. I get stuck a bit when breaking up trains or adding trains , some of the couplers will not couple irrespective whether the couplers are locked or unlocked.
Jannie.

 

[frogscale]

All I can say is that sometimes it works in some programs and not at all in others. If anybody has the last word on that issue, please be good and tell us...