Use the pagelayoutmarkers set option to control the display of the atipl markup, and the protectpagelayout set option to control whether or not it can be modified. The caret command will ignore atipl markup whenever it is not displayed, regardless of these command settings.

oid functions (for example, oid_next and oid_prev) do not recognize atipl markup whether or not it is displayed in the Edit window. Line numbering applications must be written to handle cases where atipl markup may interfere with tag or oid navigation.

The atipl singleton tags do not affect the balancing of selections, but they must be treated as pairs in other respects by all edit operations. This markup is ignored by the spell checking code, so that word fragments split by these tags are seen as a single word.

Deletion, either forward or backward, will ignore any atipl markup to the left of the cursor if it is not displayed. The deletion operation will fail if the markup is displayed and protected.

In the context of line numbering applications, the current tag is defined as the tag to the left of the cursor. The atipl tags can only be treated as the current tag when they are displayed.