Many commands work on certain regions of text. A region is defined by
the Point and the Mark The Point is the location of
the current editing point or cursor position. The Mark is the
location of a mark. The mark is set using the set_mark_cmd which
is bound to CTRL-@ (Control-2 or Control-Space on some keyboards).
When the mark is set, the m mark indicator will appear on the
status line. This indicates that a region is being defined. Moving the
cursor (Point) defines the other end of a region. If the variable
HIGHLIGHT is non-zero, jed will highlight the region as it is
defined.
Even without highlighting, it is easy to see where the location of the mark
is by using the exchange command which is bound to CTRL-X CTRL-X.
This simply exchanges the Point and the Mark. The region is
still intact since it is defined only by the Point and Mark.
Pressing CTRL-X CTRL-X again restores the mark and Point back to their
original locations. Try it.