Concepts
- mark
	
- The "other" standard position in 
	the document, which is used
	for commands which need two coordinates.
- point or current position
	
- The position where text is
	entered. The current
	position can be moved using arrow keys, the mouse and other
	methods.
- block
	
- The block is a rectangular area which 
	is displayed in inverse.
	It is used for commands which operate on a 
	whole stretch of text.
Ulric Eriksson - February 1997 - ulric@siag.nu