
Preface
The Help file contains entries for the following topics:
- INTRODUCTION:     basic concepts about DP.
- COMMAND SET:      the complete list of DP commands.
- BASIC ITEMS:      primitive drawing elements.
- POPUP MENUS:      how to use menus in DP.
- PROMPT BUFFER:    how to enter one-line strings in the Prompt buffer.
- EDITING:          how to modify the shape of existing items.
- SYMBOLS:          permanent sets of items.
- UNUSUAL COMMANDS: a popup menu with seldom-used commands.
- FONTS:            dealing with text in multiple fonts.
- LAYERS:           how to use drawings with multiple layers.
- PROFILE FILES:    personalizing DP.
- CHANGES:          differences from previous versions.

Important topics for a beginner are:
- Command Set
- Basic Items
- Editing
- Symbols

Introduction
DP is a graphic editor that allows you to create or modify drawings.
Separate programs (post-processors) exist that can extract circuit information
from schematics drawn by DP.
Documentation is available for DP and the post-processors; please contact
the maintainer for more details.

Commands to DP are single keyboard letters; case is always meaningful.
See Help for "Command Set" for the complete list of keyboard commands.
Perq keys labeled with a word are listed as all-capital letters (e.g. DEL).

All the keyboard commands may also be invoked through the Top Level Commands
Menu, which is invoked by typing a space or by pressing a button over the
small white rectangles in the middle of DP borders.

The Mouse is the main input device.
Pressing a mouse button usually starts an action; releasing the button stops it.
Commands flagged with a '*' in the "Command Set" section use the different
buttons with different meanings. 
    On 4-buttons mice, Blue is equivalent to Yellow. the Spice version of DP
    ignores the Blue button.
The lower region of the screen indicates the meaning of the different buttons
for the current command:
- left:   action for the left (or White) button;
- center: action for the center (or Yellow and Blue) button;
- right:  action for the right (or Green) button.

For instance, if the bottom line reads
        m MOVE      (Rectangle | One item | Selected)
the right (or Green) button will move all the Selected items.


Some commands prompt for keyboard input; the interaction takes place
in a Prompt Area which pops up on the screen. When the interaction is ended,
the original contents of the screen are restored. See help for "Popup Menus".
All the commands that use the pop-up Prompt Area may be aborted by typing
Ctrl-c (POS only) or by clicking outside the rectangle.
See Help for "Editing" about how to edit strings in the Prompt Area (and
elsewhere).

Some functions use Menus; while a menu is displayed the only active parts
of the screen are the menu rectangles, and keyboard commands are disabled.
See Help for "Menus".

DP can use as many windows as needed; each window has a separate coordinate
space and contains a whole drawing. Drawings may be much larger than the
Perq screen.
Clicking in the border of a window and moving the mouse with the button down
affects a window in the following way:
- gray border : move the window;
- lower-left  corner : create a new window (separate address space);
- upper-right corner : change the shape of the window;
- upper-left  corner : delete the window;
- white rectangles in the middle of the 4 edges : invoke the Top-Level Menu.

Each item in a drawing belongs to a LAYER; each layer may or may not be
displayed, altered, and output. See Help for "Layers".


--------------------------------------------
Copyright (C) Dario Giuse - 1981, 1982, 1983
--------------------------------------------

Please send bug reports and comments to:
    Dario Giuse
    Robotics Institute
    Carnegie-Mellon University
    Schenley Park
    Pittsburgh, PA 15213
    U.S.A.
      
      Office: Wean Hall 3208 - phone (412)-578-8826

Basic Items
Each DP drawing is composed of basic items and combinations of basic items
(named symbols). Basic items and symbols are always dealt with as single
elements; they may be copied, moved, deleted, and modified.

The basic DP items are:
- LINES: segments with any slope and any thickness. The endpoints of lines
  have gravity. Lines are also subject to gravity, so that their endpoints
  may be attracted by gravity points when the line is created or edited.
- CIRCLES: full circles and arcs. The endpoints of an arc have gravity.
- SPLINES: generic curves whose shape is governed by control points. Splines
  interpolate the control points (in particular, splines are tangent to the
  polygonal line that joins the points); the first and last control points
  are guaranteed to lie on the spline, and have gravity.
- AREAS: filled areas delimited by a closed polygon. The area is filled with
  a 'color', i.e. a gray level between 1 and 17.
- STRINGS: collections of printing ASCII characters. Each string is drawn in a
  specific font.
- PINS: gravity points that may be used inside symbols. Pins have gravity only
  when nested within symbols.

Basic items may be combined in permanent sets called SYMBOLS; see Help
for "Symbols".
Each basic item belongs to a LAYER: see Help for "Layers".

Command Set
-------  BASIC ITEMS
l : * Line mode (DOWN = start line, UP = freeze line)
L :   Rectangle mode (4 lines) (DOWN = start, UP = freeze)
0 : * Circle mode (DOWN = start, UP = freeze). Green uses 3 points.
9 : * Spline mode: enter control points (Yellow, White) and create
      a spline using the existing control points (Green).
8 : * Area mode: enter vertices of the polygon (Yellow, White) and create a
      filled area to fill the polygon (Green).
p : * Pin mode. Green generates progressive pin numbers.
e : * edit existing items. See Help for "Editing".
- :   set the default thickness of lines, circles, splines
n : * New Parameters: change the thickness, font, etc. of existing items
-------  STRINGS
a : * Ascii String mode. Green: enter a sequence of strings, terminated by an
      empty line. Others: enter one string.
f :   set the new Current Font, enter new fonts, or delete fonts. See Help
      for "Fonts".
-------  SYMBOLS
b : * create new Symbols, starting from basic components.
B : * Unpack Symbols into their basic components.
t : * Transform Symbols; uses a menu of commands.
-------  SELECT
s : * Select
S :   select all the items in the current window
z : * Deselect
Z :   deselect all the items in the current window
-------  COPY, MOVE
c : * Copy; move the copy around until the button is released.
m : * Move until the button is released.
x : * Move items and Stretch connected lines.
-------  DELETE
d : * Delete
D :   delete all the selected items in the current window.
u :   Undelete
-------  LAYERS
v :   display the Layers menu and set various layer parameters.
-------  FILES
I :   read a drawing from a file into the current window (merge).
i :   read one symbol definition from a file, put it at the current position.
j :   read a text file, creating DP strings.
@ :   read commands from an alternate input file.
o :   write the drawing in the current window to an output file.
H :   generate a hardcopy of the drawing in the current window.
-------  DISPLAY
R :   redraw the whole screen
r :   redraw the current window
g :   go to the next Grid in the grid list and set the Mouse Grid to its value.
` :   (toggle) display the Display Grid.
w :   move the image inside the current window
= :   new scale for the current window (real number)
-------  MISCELLANEOUS
  :   [space bar] display the Top-Level Commands Menu.
k :   Unusual Commands: change the value of some parameters. The current
      setting of the parameter is always displayed. See "Unusual Commands".
q :   quit (checks if modified buffers exist before quitting).
INS (ESC): set a mark at the center of the current window (remember position).
DEL:  delete the last-visited mark from the window.
G :   go to the next mark in the circular list, center the window around it.
? :   print deleted items, coordinates, storage, symbol definitions.
h or HELP: type this text.

Popup Menus
DP uses popup menus as a way to enter values or select alternatives.
A popup menu is a sequence of strings (the different options) enclosed in a
black rectangle. The area within the rectangle is called the Menu Area;
its original contents are restored when the menu is terminated.
The following defines the behavior of menus:
- An option from the menu is selected by pressing any button over the
  string that defines the option.
- A menu may be aborted by typing Ctrl-C (POS only) or by pressing any button
  outside the Menu Area.
- An aborted menu has no action whatsoever; the command is ignored.
- It is meaningless to type any character while the popup menu is being
  displayed. The character is ignored and a 'Beep' signals the error.
- Most menus accept only one button press at a time; when this is the case,
  the menu disappears immediately after the button press. In some cases ('k'
  menu, for instance) several presses are allowed; the menu is then
  redisplayed after each press. To exit such a menu, abort by pressing
  outside it.

If the whole menu cannot be displayed, a small scroll bar is created at
the bottom (POS only). Items in the menu may be scrolled up or down
by pressing any button in the scroll area and moving the cursor to the left
or to the right while holding the button down.

The following commands use popup menus:
 : (space) Top Level Commands Menu. Contains all the commands that
   may be invoked with a single keystroke. It is thus possible to select
   any command without touching the keyboard.
k: unusual commands. This is a menu of commands that are not frequently used
   and do not have a key assigned to them.
f: select the default font, or update the Fonts table.
t: transformations (the popup menu is used to select the transformation).
n: new parameters (the popup menu is used to select which parameter
   should be altered).
i: input a single symbol from a file (the menu is used if a Parts File has
   been read).
h: get some help.
v: special Layers menu. See Help for "Layers".

Some commands (f, n, k) may use sub-menus as required.

Notice that the Layers command ('v') does not use the regular popup menus.

Prompt Buffer
All the commands that require the user to type a string use a popup Prompt
Buffer. This is small buffer that can accommodate only one string and a
header.

The header is in the upper portion of the Prompt Buffer, and may
suggest a default within square brackets. When a default is suggested,
typing a Return or pressing Green accepts the default.

The string in the Prompt Buffer may be edited using the standard string edit
mechanisms (see Help for "Editing").

The Prompt Buffer may be aborted by pressing any button (other than Green)
outside the Prompt Buffer, or by typing Ctrl-C (POS only).

Unusual Commands
The 'k' command is a popup menu of seldom-used functions that do not have
a keyboard command of their own.
The Unusual Commands Menu allows repeated choices; when all the desired
functions have been executed, the menu should be aborted by clicking any
button outside the rectangle.

Functions that assign a value to some variable always display the current
value of the variable.


The 'k' menu contains the following functions:

checkpoint              number of keystrokes in this window between checkpoints.
display grid            set the size of the Display Grid in this window.
mouse grids             enter the Grids Menu. Grids may be modified (i.e., the
                        numerical value may be changed), added, or deleted.
gravity                 set the value of the gravity field (0 means no gravity).
center files            if true, center files in 'I' and 'o'.
rename redefined        if true, redefined symbols are renamed instead of
                        changed to the new definition.
read symbols file       read a Parts file for the 'i' command.
toggle cursor shape     change the direction of the cursor arrow.
display diamonds        display small black squares ('diamonds') at the
                        intersections of two or more lines (other than
                        end-corners). Non-permanent display change.
display in black mode   redisplay the whole screen using Black instead of
                        Invert. Non-permanent display change.
fill areas              if true, areas are displayed as filled with a gray
                        level; if false, only the edges are shown (faster).
pin numbers             display pin numbers. Permanent display change.
pins                    display the position of pins. Permanent display change.
send to plotter         plot the drawing on an HP 7221A pen plotter.
clip (Press file)       if true, clip the drawing to the current window
                        when generating a Press file.
diamonds (Press)        if true, print diamonds in Press files.

Editing
The action of the Edit function depends on the particular mouse button
being used and on the kind of item being edited.

LINES:

A line is edited by holding one of the buttons down over the line and
moving the mouse. The nearest endpoint of the line becomes connected to the
cursor and is dragged as the mouse is moved. Releasing the button freezes
the line; if gravity was used, the endpoint may be attracted be a nearby
gravity point.
- Yellow: constrained slope (horizontal, vertical, or 45 degrees) with gravity.
- White:  generic slope, with gravity.
- Green:  generic slope, without gravity.


CIRCLES:

A circle or arc may be "opened" for editing by pressing a button near one
of the endpoints (remember that in a full circle the two endpoints coincide
and are at the rightmost point of the circle, i.e. at the intersection
with the positive X axis).
Once editing starts, the radius or the endpoint becomes connected to the
cursor and is dragged as the mouse is moved.
Releasing the button freezes the circle.
Button assignments:
- Yellow: modify the radius of the circle.
- White, Green: modify one of the angles, holding the radius constant. The
  nearest endpoint will follow the cursor.
One way of creating an arc is thus to create a full circle and to edit it
using White or Green.


SPLINES:

A spline is opened for editing by pressing any button near one of the
endpoints. While the spline is open, its control points are displayed as
black rectangles. The spline may be edited by pressing White or Yellow over
a control point and moving the mouse with the button down; the control point
follows the cursor and the spline is modified accordingly.
The Green button closes the spline; the control points are then erased
and another item may be edited.

AREAS:

A filled area is edited like a spline, by opening it first (clicking near
any vertex) and then dragging vertices. The area is dynamically adjusted to
follow the vertex.

Filled areas are closed by pressing Green; the vertices are erased and
another item may be edited.


STRINGS:

A string is always modified around the Pencil position (the Pencil is a
small vertical bar between two characters).
Strings in a Prompt buffer may be aborted by pressing Yellow or White when
the cursor is OUTSIDE the Prompt buffer. This is equivalent to
typing a Ctrl-C (POS only).

The following cursor commands may be used to edit strings:
- White: position the Pencil (only if the cursor is within the string
  boundaries).
- Yellow: position the Pencil (only if the cursor is within the string
  boundaries); delete the NEXT character, i.e. the character to the right
  of the Pencil.
In addition, the following commands behave exactly like in the Spice line
editor:
^a: go to the beginning of the string.
^b: backward one character.
^c: (POS only) abort string editing, leave string unchanged.
^d: delete the character after the Pencil.
^e: go to the end of the string.
^f: forward one character.
^h or BACK SPACE: delete the previous character.
^k: delete to end of line.
^m or RETURN or Green: finish editing this string.
^q: quote the next character.
^r: reverse search for the next character to be typed.
^s: forward search for the next character to be typed.
^t: transpose the two characters before the Pencil.
^u or OOPS: delete from beginning of line to the Pencil.

Notice: control characters should not be inserted in DP strings, as a rule.
In particular, DO NOT try to insert a Return or Line Feed in the string
using the ^q mechanism. The resulting file could not be read back.


PINS:

Editing a pin means changing the position of the pin number.
A pin is opened for editing by pressing any button exactly over the pin and
moving the mouse around.
The pin number may be in any of the four quadrants, and is redisplayed in
the new position as the cursor is moved around the pin.


SYMBOLS:

- Yellow, White: display the name of the symbol at the bottom of the screen.
- Green: open the name of the symbol for editing. The name is edited as
  a regular string; the old name is effectively deleted.
  It is illegal to rename a symbol to a name that is already in use.

Symbols
Groups of primitive elements (lines, etc.) may be combined to form Symbols.
A symbol behaves like a primitive element; in particular, it may be nested
within other symbols.

Symbols are very inexpensive to create and maintain; their use is strongly
encouraged, since they represent an important method of structuring a
DP drawing. The general idea is that "if you needed it once, you may need it
again". Items that are logically related (the four lines in a box,
a group of items that is repeated more than once in a drawing, etc.) should
almost always be packed in a symbol. Symbols and Layers together can make
the long-term maintenance of a DP drawing much simpler.

Three distinct elements form a 'symbol':
- a symbol DEFINITION, i.e. the original group of items that were combined
  together. The Symbol Definition is a description of the unretouched symbol,
  and may be modified by individual calls.
- a symbol NAME, i.e. a string that uniquely identifies each definition.
  No two symbol definitions in a drawing can share the same name.
- any number of symbol INSTANCES, i.e. calls to the definition. Each instance
  specifies that the symbol, as defined by the Symbol Definition, should be
  displayed at a specific position in the drawing. Symbol Transformations
  may be applied in the process, so that an instance may actually differ
  from the definition because of rotation, scaling etc.

All the instances of a symbol are effectively pointing to the original
definition, so that if the definition is modified all the instances are
modified as well. Single instances do not have an individual name: their
'name' is the name of the Symbol Definition.


PACKING AND UNPACKING

A Symbol Definition may be created by packing a group of items with the
'b' command. When the definition is created, a Symbol Name is required; the
user is prompted for a string. If an empty string is typed, DP generates
an automatic name.
A definition may be renamed using the Edit command, as long as the new
name is not in use.

A Symbol Instance (NOT definition!) may be unpacked with the 'B' command.
This operation deletes the Symbol Instance and replaces it with the list
of items in the Symbol Definition. Notice that the new items may be different
from the ones in the original definition, since the instance may have
been transformed. In other words, the new items 'look' exactly like the
instance before unpacking.

A Symbol Definition cannot be explicitly deleted. Definitions are
automatically deleted when no longer referenced.


TRANSFORMATIONS

As mentioned above, Symbol Instances may be transformed through the 't'
command. Each instance may have its own independent transformation.
As a consequence, DP items should always be packed in a symbol if a
transformation is desired.

All the transformations in DP are relative to the CENTER of the Symbol
Definition, which is defined as the center point of the
bounding rectangle of the definition.
This choice makes transformations independent of the order of application:
scaling an instance and then rotating it is equivalent to rotating first
and then scaling.

Layers
A drawing may contain several Layers; each layer may be thought of as a
transparency. Individual transparencies may be added or deleted at will.

Each Layer has three attributes that determine its status:
- DISPLAY: if ON, objects drawn on the layer are visible and have gravity.
- ALTER:   if ON, objects drawn on the layer may be modified by regular
           DP commands.
- OUTPUT:  if ON, objects drawn on the layer may be output to a DP file.

Following the 'what you see is what you get' philosophy, the Display
parameter also determines whether a layer will be output in a Hardcopy
command.

Symbol Instances act as FILTERS in regard to Layers. Imagine, for instance,
that the items in a symbol are drawn on Layer A, but an instance of the
symbol is created in Layer B. If Layer B is visible, the items will or will
not be displayed according to the status of their own layer (i.e. layer A).
If, on the other hand, Layer B is NOT visible, nothing will be displayed,
even though the individual items are themselves on a visible layer.
In other words, the symbol instances is 'filtering' the nested items: since
the instance is on a non-visible layer, everything inside it is automatically
filtered out. The nested items are not even considered (this may result
in considerable redisplay speed-ups).

THE LAYERS MENU.

The parameters for individual layers may be set using the Layers command
('v'). This command displays the Layers Menu, which behaves as a Popup Menu
but has a different format and mode of operation.

The upper portion of the Layers Menu is a matrix of all the existing layers
and the current setting of their paramters. The names of the layers are
listed on the right side; the 3 parameters are listed on top. A fourth
vertical column is reserved to display the Current Layer.
If a parameter for a layer is ON, the corresponding position in the matrix
is displayed in black; otherwise, the position is white.

Individual parameters may be inverted by pressing any button over the
corresponding position. Note that when a layer is set to non-visible by
clicking over the Display position, also the Alter parameter is turned off.
This is intended to prevent invisible layers from being accidentally modified.

Exactly one layer at a time may be chosen as the Current Layer. This means
that new items will automatically be placed in the Current Layer.


The lower part of the menu contains additional commands which may be
activated by pressing any button over them:
- NEW LAYER: create a new layer with a new name. New layers are set by
  default to Display-Alter-Output ON.
- RENAME: change the name of an existing layer. The new name may not be already
  in use.
- DELETE: delete a layer. Neither the Current Layer nor layers that are
  still in use (i.e. that are referenced by at least one item) may be
  deleted.


Just like any other Popup Menu, the Layers Menu may be aborted by pressing
any button outside the enclosing rectangle (or by typing ^C, POS only).

Fonts
ASCII strings may use different fonts. The different font specifications
are kept in the Fonts Table, displayed by the 'f' command. Each font has
two independent parts in its specification:
- the 'abstract' definition of the font, more or less device-independent.
  This defines the font family, the size, the rotation, and the face-code
  of the particular font.
- the Perq font to be used to display the strings on the Perq screen. This
  is the name of the file that contains the Perq font.

This means that, for instance, the same Perq font may be used to display
several 'abstract' font definitions. A device with more font definitions, such
as the Dover printer, will use more fonts for the same job.

The following parameters identify the abstract font definition:
- FACE: one of the following:
  r (roman), b (boldface), i (italics), bi (boldface italics);
- SIZE: the size of the font within the given family, as an integer
  (usually 6..16; larger numbers mean larger fonts);
- ROTATION: the rotation of the font, expressed in degrees from the positive
  X axis (e.g., 0 for this font, 90.0 for landscape fonts);
- FAMILY: the font family (e.g. Gacha, Helvetica, TimesRoman).

The PERQ FONT is the filename of the Perq font used to display the font.

Profile Files
DP may be invoked with a Profile file. This allows to set several options,
as well as configuring the program to any initial state.

To do this, the program should be called with the switch /profile in the
command line:
        DP /profile=filename

Alternatively, under POS, one can have an entry in the default system
profile file:
        #DP
        filename


'filename' should be the name of a text file that contains the initial
options. The format of the file is generally very simple: each line contains
a keyword followed by a value.
Keywords must always be spelled out completely; case does not matter.
Boolean options take the two values 'on' and 'off'.
Comments are indicated by a ! at the beginning of a line.


When DP is started it always sets all the possible options to their default
values. Reading a profile file only affects the named options; the other
values are unchanged. This also applies to errors in the profile file:
erroneous options are ignored and the default value is used.



The following keywords are recognized. If a default value exists, this is
always indicated in upper case.

!               enter a new window (coordinates of the corners)
begin-window            0 12 767 1023
!               center files on 'I' (empty windows only)
center-files            ON
!               set numbers of keystrokes between checkpoints
checkpoint              200
!               fit the window to a page (Press files only)
clip-press-on-window    ON
!               define a subset of commands for the Commands Menu
commands-file           filename
!               default color
def-color               1
!               define a new font and make it the default
def-font                GACHA 7 R 0 GACHA7
!               define a new layer and make it the default
def-layer               STANDARD RWO
!               default thickness
def-thickness           1
!               print diamonds at line intersections (Press files only)
diamonds-in-press       OFF
!               enter a new font definition
font                    GACHA 7 R 0 GACHA7
!               display function and mouse buttons in the cursor (POS only)
function-in-cursor      ON
!               gravity field
gravity                 5
!               enter a new layer definition
layer                   STANDARD RWO
!               display the command character in the menu and function
menu-character          ON
!               read a parts file (symbol names - file names) for 'i' command
parts-file              filename
!               display pin numbers
pin-numbers             OFF
!               display pin positions
pin-positions           OFF
!               rename redefined symbols
rename-symbols          OFF
!               append .DP extension by default
use-extension           ON


The following options are only recognized in Window mode (i.e., between
a begin-window and an end-window):

!               set the alternate mouse grid
alternate-grid          1
!               set the display grid
display-grid            6
!               close this window definition
end-window
!               scale for this window (real number)
scale                   1.0
!               show the display grid
show-grid               OFF

Changes
        VERSION 6.1

1) Added a new type of basic element: Filled Areas. These are polygons that
   are filled with a gray level, from 1 (black) to 17 (white). Filled areas
   are governed by their vertices, strictly analogous to the control points
   of a spline.

2) Added string editing a la Spice line editor. Most of the Emacs control
   characters are implemented, including full filename expansion (but excluding
   filename listing, ^?). See Help file for "Editing".

3) The endpoints of arcs and splines have gravity.

        VERSION 5.25

1) Added an option to delete a layer (in the Layers Menu, 'v').

2) It is no longer possible to invert all the parameters in a vertical column
   of the Layers menu at once. Also, the special commands at the bottom of
   the Layers Menu prompt for the name of the layer in a more reasonable way.

3) Mouse Grids in a window are now organized as a circular list. It is possible,
   for instance, to have three values of the Mouse Grid and to cycle through
   them with the 'g' command.
   The list of grids may be altered with a sub-menu in the 'k' command. This
   menu shows the current list for the current window; the current value of
   the grid is always AT THE TOP of the menu.
   A value is modified by clicking over it. New values may be added (ADD) or
   deleted (DELETE); at least one grid must be present.

        VERSION 5.16

1) Created a Profile file mechanism. All the initial configuration of
   DP may now be set through a profile file.
2) Moved the Plotter command to the 'k' menu.

        VERSION 5.13

1) The Layers menu is now a top-level command (' ', space bar).

2) The Display Diamonds command has been moved to the k menu.

        VERSION 5.10

1) Added the Rectangle command ("L"), which creates a rectangle with 4 lines.
   This is analogous to the Line command; gravity is be used with
   the same buttons.

2) The hor/ver button in Line draws a 45 degrees line if the cursor is
   close to 45 degrees (i.e.,  40 < (angle mod 90) < 50 ).
   This means there are now three possible constrained lines: 0, 45, and 90
   degrees.

3) Added a command to delete fonts (in the Font menu).

4) Fixed rotated strings. 180- and 270-degrees rotations on fonts now
   do a reasonable thing: the string is always readable, but it moves
   in the opposite direction when it is being typed.

        VERSION 5.8

1) Transcript files may be slowed down or stopped during replay.
   1. A delay may be specified with the transcript file name. Default is
      0, i.e. no delay; maximum delay is 32767.
   2. Transcript replay may be stopped at any time by
      pressing any mouse button; releasing the button continues the replay.

        VERSION 5.7

1) If a name is typed after "dp" on the command line, the DP file with that
   name will be read in.
   If an @ precedes the file name, the file is used as a transcript file.
   Examples:
   dp mfcell      will start DP and read the file 'mfcell.dp'
   dp @replay     will start DP and read commands from the file 'replay'.

   ------  VERSION 5.5

1) Write-protected items are now totally invisible to the "x" command.

2) The "x" command has been modified to work also for STRINGS (as usual, this
   applies only to the White button): if a line has the string as its signal
   name, the line is stretched. That is, a string behaves exactly like a
   symbol.

