command) append
	synopsis) [offset]a
	description) add some lines of text after offset line
	description) default offset is current line
	error) a buffer error when offset is unreachable
	implementation) implemented
command) insert
	synopsis) [offset]i
	description) insert some lines of text before offset line
	description) default offset is current line
	error) a buffer error when offset is unreachable
	error) a buffer error when trying to insert before line 0
	implementation) implemented
command) delete
	synopsis) [offset|range]d
	description) delete one line or a range of them
	description) default offset is current line
	error) a buffer error when trying to delete out of file
	implementation) implemented

command) change
	synopsis) [offset|range]c
	description) delete one line or a range and append there
	description) default is current line
	error) a buffer error when trying to delete out of file
	implementation) implemented

command) edit
	synopsis) e filename
	description) loads a new file in the buffer
	error) file not found
	implementation) implemented

command) edit shell
	synopsis) e !shell
	description) load the output of a command in the buffer
	error) errors from systems , coming from the shell command execution environment
	implementation) implemented
	
command) write
	synopsis) w [filename]
	description) write the buffer to a file
	description) if argument is missing, write to the filename set
	error) a -filename not set- if buffer has no filename 
	implementation) implemented

command) filename
	synopsis) f [filename]
	description) set or get the filename buffer
	error)
	implementation) implemented
command) undo
	synopsis) u
	description) bring the buffer back to before last modification
	error) a -no more states- if the first state remembered is hit
	implementation) implemented
command) redo
	synopsis) R
	description) put the buffer ahead one state, if no modifications happened after last undo
	error) a -no more states- if redo states stack is empty
	implementation) implemented