SET(INSERT)
  Sets or changes the mode for entering text in the specified buffer to
  insert.  New characters appear in front of the current position, pushing
  existing characters to the right.  This is the default setting.
  Syntax
     SET (INSERT, buffer)
  Example
     SET (INSERT, CURRENT_BUFFER);
  Sets the mode for entering text in the current buffer to insert.
  Related topics
     COPY_TEXT   MOVE_TEXT   SET(OVERSTRIKE)