SET(SYSTEM)

  Makes a buffer a system buffer.  This is useful when creating your own
  editor in which you want to distinguish system buffers, such as a paste
  buffer, from those that users can edit.  TPU does not handle system
  buffers differently from user buffers; TPU merely keeps track of which
  buffers have been designated as system buffers.  It is the application
  layered onto TPU that gives system buffers their special
  characteristics.

  Once a buffer is made a system buffer, it cannot be reset to being a user
  buffer.

  Syntax

     SET (SYSTEM, buffer)

  Example

  The following statements create a paste buffer and make it a system
  buffer:

     paste_buffer := CREATE_BUFFER ("paste");
     SET (SYSTEM, paste_buffer);

  Related topics

     SET(MODIFIABLE)   SET(NO_WRITE)   SET(OUTPUT_FILE)   SET(SYSTEM)