Local Screen Tags exist on the Client. If multiple Clients are viewing the same display, each client will have a different value for that screen tag. These are not "Global" hence the term "Local".
Local Tags are available only within a given graphic display. Once that display is closed or a new display called, the Local Screen Tags are lost and the values within them lost.
Local Screen Tags are built using DRAW. The have no alarming and few of the features of IO Tags.
Local Tags are not limited by tag count. Screen tags are useful in creating animation and calculations for use in graphic displays without using up constant tag, calculation tag or Accumulation Tag.