Syntax:  SET PENDING DELETE boolean

  Specifies whether or not a selection in a user buffer is deleted when
  a user inserts text.

  By default, this command is disabled (the parameter value is off).
  To delete selected text when you insert text, specify this command
  with the parameter value on.  This command is automatically disabled
  for a selection made with the SELECT ALL command.

  RELATED COMMANDS:

     RESTORE                     SELECT ALL