Release 10.1A: OpenEdge Development:
ADM Reference

linkState

Receives messages and republishes events when a GroupAssignTarget becomes active (when it is viewed) or inactive (when it hidden).

Location: viewer.p

Parameters:

INPUT pcState AS CHARACTER

Active or Inactive — The event is republished up the groupAssignSource and the DataSource which then runs linkStateHandler if the link cannot be deactivated.