OPTIONS
This section describes the various options which may be selected to
control or qualify the operation of the Editor.  The initial parameters
in the list marked with an asterisk can be specified only in the command
line when the Editor is called (see CALLING THE EDITOR); that is, once
established, they cannot be changed.  The others may be freely altered
at any time, by means of the Environment command "%E"(below).



Pre-definition file    *PRE

 This Option is provided to make it possible to specify a file of
 editing commands which are to be obeyed at the outset of the editing
 session.  Its main use is to permit frequently used definitions to be
 recovered from a file, but the file may contain any editing commands
 and may in fact comprise a complete edit ending with the Close command
 ("%C").  Values for this parameter must be valid file-names.  Although
 PRE may be specified at the outset only, the %G command (Get editing
 commands from file) is available at any time.

Examples:    -PRE=WPPREDEF    -PRE=ECUU99.PROJ_DEF1


Terminal type          *TTYPE
 The parameter TTYPE informs the Editor what type of interactive
 terminal is being used and hence defines the terminal characteristics,
 including the screen length and screen width.  Values for this
 parameter are numbers in the ERCC enumeration; the default value is the
 system-defined TERMINALTYPE, and in general this should be appropriate.

Examples:    -TTYPE=12        -TTYPE=13
              {VT100}          {Esprit}


Window dimensions      *WTOP, *WROWS, etc
* WTOP  -- window top      Default: 0        Range: 0..VROWS-1
* WROWS -- window rows     Default: VROWS-2  Range: 1..VROWS-2
* WLEFT -- window left     Default: 0        Range: 0..VCOLS
* WCOLS -- window columns  Default: VCOLS    Range: 0..VCOLS
* CTOP  -- command top     Default: WROWS    Range: 0..VROWS-2
* CLEFT -- command left    Default: 0        Range: 0..39
* CCOLS -- command columns Default: VCOLS    Range: 40..VCOLS

 These parameters define the two screen regions to be used by the
 Editor.  The 'top' values are in terms of row numbers ranging from zero
 at the top of the actual screen to VROWS-1 at the bottom; VROWS is
 typically 24.  The 'left' values relate to columns, numbered from zero
 at the left of the actual screen to VCOLS-1 at the right; VCOLS is
 typically 80.

 The first four define the total extent of the screen region to be used
 for displaying the file being edited.  The window height, as defined by
 WROWS, may be anything from one row up to the full screen height less
 two rows.  A one row window obviously gives a rather blinkered view of
 the file.


 The width of the window, as defined by WCOLS, may be anything from one
 column to the full screen size.  A one column window is obviously daft.

 The parameters CTOP, CLEFT and CCOLS define the position and width of
 the two-row region used for commands and reports.  CTOP specifies the
 first of the two rows.  The minimum width for the command region, as
 defined by CCOLS, is 40.

 Usually when the Editor is called directly by the user from system
 command level, it is appropriate for these two regions to occupy the
 full screen, but when the Editor is called from within another package
 or if the user wants to preserve other information on the screen, a
 smaller effective screen area may be specified.  The Editor neither
 clears nor wittingly modifies areas outside the regions specified by
 these parameters.

 With the default values, the command region occupies the last two rows
 on the screen and the file window the remainder.


Effective window       *MAXWIN, MINWIN
* MAXWIN -- maximum window    Default: WROWS  Range: 1..WROWS
  MINWIN -- minimum window    Default: ?      Range: 1..WROWS

 The purpose of these Options is to make it possible to control the
 volume of text which is transferred to the screen at any one time to
 show the state of the file.  The number of lines used within the
 available window area is allowed to vary between the limits specified
 by MINWIN and MAXWIN.  The principle is that when the focus of editing
 moves to a completely new site in the file, only MINWIN rows are
 displayed in the lower part of the available window area.  During local
 manoeuvres, this minimum display is extended as appropriate up to the
 selected maximum. (What operations permit extension depends on the
 video characteristics and the position and width of the window).
 MAXWIN determines the maximum number of lines to be used for the time
 being, the remainder of the The MAXWIN parameter selects the amount of
 the file window which is to be used at the outset, the remainder being
 reserved for secondary input, or subsequent expansion through
 increasing MINWIN.


 When a secondary input file is being processed, it has its own varying
 size window at the top of the overall file display region defined by
 WTOP and WROWS, originally as determined by MAXWIN (or a default value
 if MAXWIN is zero).  When a new MINWIN value is selected (by %D or %E),
 it alters the secondary input value if secondary input is selected at
 the time, rather than the main file MINWIN value.  Whenever an
 increased minimum value is selected for secondary input, this has the
 effect of constraining the maximum size of the main file's effective
 window, and conversely.

 Where there are no performance restrictions imposed by communication or
 processing systems, the upper limit value (WROWS) is usually
 appropriate for MINWIN.  The default value is chosen according to the
 system.


Text line width        WIDTH, MARGIN
 The parameter WIDTH specifies the maximum line length to be used in
 connection with the Adjust and 'At' commands (and for failure
 conditions in the case of Insert and Join).

 The initial default value is 80.


 The parameter MARGIN specifies a left margin position, which defines
 the effective start of the line.  This determines where the file
 pointer is placed following a Move or Move back command, and is also
 relevant to the operation of the Adjust command.  WIDTH is inclusive of
 MARGIN.

 The initial default value is zero.


Letter-case matching   MATCH/NOMATCH
 When matching text strings in the course of executing any of the
 commands Find, Delete, Traverse, Uncover or Verify, the Editor may or
 may not ignore case distinctions between letters.  By default it
 ignores them.  This mode of matching may be switched off by selecting
 the option NOMATCH and re-established by selecting the alternative
 option MATCH.  When it is switched off, letters in text parameters are
 matched exactly as typed against letters in the file.
 The setting of this mode does not affect text parameters for the
 insertion commands, which are always inserted exactly as typed.


Displaying pointer     HILIGHT/MARK

 This parameter controls how the current position of the file pointer is
 displayed when the Editor is in command mode.  The options are HILIGHT
 or MARK.  HILIGHT implies use of whatever capability a video has for
 distinguishing arbitrary characters, for example, reduced or increased
 intensity, underline, or (preferably) reverse video.  Its use may
 require particular switch settings or intensity adjustments on the
 terminal.
 MARK implies the technique of overwriting the character immediately to
 the left of the current position with a distinguished character
 (splodge or tilde).  An additional column is inserted at the beginning
 of each line in this mode, for use when the pointer is at the beginning
 of the line.  MARK is appropriate for terminals which have no means of
 highlighting individual character positions.


Updating strategy      LATE/EARLY

 The default strategy for updating the window is to do so only when the
 material in it is changed or the file pointer is moved outside it.
 Selecting EARLY causes the window to be extended or refreshed when the
 bottom line is reached rather than when it is passed.  The default may
 be restored by selecting LATE.