Manipulation of Selections
Three commands can manipulate a selected region.
• copy_mark — causes the selected region to be copied into the paste buffer.
• clear_mark — deselects a selected region.
• delete_mark — cuts the selected region and puts it into the paste buffer.
Usually, the delete_mark command is performed only when the region has balanced tag pairs. Unbalanced regions are allowed, however, if tags can be inserted such that the document remains in context.
Failure of any of these commands causes the $status variable to be set to 1.