edit  -- Command, zero or one input.  Abbreviation: ed
     The input to this command must be a word, which is the name of a  pro-
     cedure,  or a list of words, each of which is the name of a procedure.
     (Unlike the to command, but like all other Logo procedures,  the  edit
     command  evaluates  its input, so you must use a quotation mark before
     the procedure name, if only one is given, to indicate that it  is  the
     name  itself which is the input to edit; otherwise Logo would actually
     run the procedure to calculate the input to edit.)  The procedure  you
     name  may  or  may  not already be defined.  Logo responds to the edit
     command by running the text editor edt, editing the definition of  the
     procedure(s)  named  in its input.  (If a procedure was not previously
     defined, Logo creates an initial definition for it which contains only
     a  title  line and the end line.) You then edit the definition(s) with
     edt.  When you write the file and leave edt, Logo will use the  edited
     file  as the definition(s) of the procedure(s).  You must not put any-
     thing in the file except procedure definitions; in other words,  every
     nonempty  line  in  the  file must be between a "to" line and an "end"
     line.

     If the edit command is given with no input, edt is given the same file
     as  from  the last time you used the edit command.  This is a conveni-
     ence for editing the same procedure(s) repeatedly.

     If, while editing, you change your mind and want to leave edt  without
     redefining  anything, use the command ESC ^Z instead of the normal ^Z.
     This special way of leaving edt tells Logo not to redefine  your  pro-
     cedures.   You  have the choice, before exiting edt, of writing or not
     writing the temporary file which contains  the  definitions.   If  you
     don't  write the file, another edit command with no input will re-read
     the previous contents of the temporary file; if you do,  another  edit
     will re-read the new version.

     If your Unix environment contains a variable named  EDITOR,  the  con-
     tents  of that variable is used as the name of the text editor program
     instead of the standard edt.  The variable can contain  a  full  path-
     name,  or  just  a program name if the program can be found in /bin or
     /usr/bin.  Your favorite editor may not have a facility like edt's ESC
     ^Z to abort redefinition.
