ALLOCATE-RESOURCE f NAME
   NAME is assumed to be a resource symbol.  (See resource.)
   If there are any of the resource available, snarf one and
   return it.  Otherwise, cons one up and return that.
BLINKER ns
   A little flashing thing on the screen used to mark a position
   in exciting and useful ways.
BLINKER-ARG1 sm BLINKER
   This is the first auxiliary argument to BLINKER-FUNCTION, qv.  For
   example, it might be the width of the area to complement in a 
   rectangular complementing blinker.
BLINKER-ARG2 sm BLINKER
   This is the second auxiliary argument to BLINKER-FUNCTION, qv.  It 
   could be the height of a rectangular complementing blinker.
BLINKER-DESELECTED-VISIBILITY sm BLINKER
   What the blinker should do when the sheet it is on is deselected.
   Reasonable values are :ON, :OFF, and :BLINK.  See BLINKER-VISIBLILITY.
BLINKER-FUNCTION sm BLINKER
   When it is time to blink the blinker, apply this function to the
   blinker, BLINKER-ARG1 and BLINKER-ARG2, qqv.
BLINKER-HALF-PERIOD sm BLINKER
   When the blinker is blinking, wait this many sixtieths of a second
   between blinks (complementations)
BLINKER-PHASE sm BLINKER
   What part of the blinking cycle are we in?  For a complementing 
   blinker, NIL means off and T means on.
BLINKER-SHEET sm BLINKER
   The sheet the blinker is on.
BLINKER-TIME-UNTIL-BLINK sm BLINKER
   How long until next blink, in sixtieths of a second.  NIL means not
   blinking.
BLINKER-VISIBILITY sm BLINKER
   A flag that controls the blinker's dynamic behavior.
   Possible values:
      NIL means the blinker is invisible
      T means it is visible but dull
      :BLINK means it is blinking now
      :ON means that it is stuck on but will blink when selected
      :OFF means that it is stuck off but will blink when selected
BLINKER-X-POS sm BLINKER
   X coordinate of left edge of blinker.
BLINKER-Y-POS sm BLINKER
   Y coordinate of top edge of blinker.
DEALLOCATE-RESOURCE f NAME RESOURCE
   NAME is assumed to be a resource.  Return RESOURCE to the free
   pool of such things.
DECLARE-INSTANCE-IMMEDIATE-INSTANCE-VARIABLES m (NAME) . BODY
   *****
DEFINE-SHEET-FLAGS m &REST FLAGS
   Define accessor macros for getting at various fields of the FLAGS
   instance variable of flavor SHEET.
DEFINSTANCE-IMMEDIATE m NAME . INSTANCE-VARIABLES
   *****
DEFRESOURCE m NAME . CREATOR
   Define a resource (qv) called NAME with manufacturer CREATOR.
   If the resource is unbound it is set to NIL but if it is bound
   its binding is assumed to be the initial supply and is left 
   untouched.
DELAYING-SCREEN-MANAGEMENT m &REST BODY
   Bind INHIBIT-SCREEN-MANAGEMENT to T, telling the screen management
   functions to queue their operations on SCREEN-MANAGER-QUEUE instead
   of immediately performing them.  Then perform BODY.   No matter what
   happens in BODY, check to see if we are back out at top level, and if
   we are, do all the queued screen management operations.
DOPLIST m (PLIST PROP IND) . BODY
   For each indicator-property pair in PLIST, do the BODY with PROP
   bound to the property and IND bound to the indicator.
edge
   A number representing either the horizontal offset of a vertical
   line or the vertical offset of a horizontal line.
inside edge
   An inside edge of a SHEET lies inside the physical edge by the
   width of the margin.
IO-BUFFER ns array-leader
   Input/output buffer implemented as an array with input and output 
   pointers circulating through it to form a FIFO buffer.
IO-BUFFER-EMPTY-P m BUFFER
   Determines whether or not the buffer is empty.
IO-BUFFER-FILL-POINTER sm IO-BUFFER
   Fill pointer, unused
IO-BUFFER-FULL-P m BUFFER
   Determines whether or not the buffer is empty.
IO-BUFFER-INPUT-FUNCTION sm IO-BUFFER ?
   Function to be run on inputting data in case data needs to be
   massaged 
IO-BUFFER-INPUT-POINTER sm IO-BUFFER
   Index in which data is next to be stored
IO-BUFFER-OUTPUT-FUNCTION sm IO-BUFFER ?
   FUnction to be run when taking data out
IO-BUFFER-OUTPUT-POINTER sm IO-BUFFER
   Index from which data is next to be taken
IO-BUFFER-PLIST sm IO-BUFFER
   A property list holding various pieces of miscellany, like
   whether or not the buffer is in super-image mode.
IO-BUFFER-SIZE sm IO-BUFFER
   Size of I/O buffer
IO-BUFFER-STATE sm IO-BUFFER
   Tells what operations are safe at the moment.
   Possible values:
      NIL means any I/O operation is OK.
      T means no I/O operation is OK.
      :INPUT means data may only be put in.
      :OUTPUT means data may only be taken out.
LOCK iv SHEET
   If null, the sheet is unlocked.  If a list, the sheet is
   temporarily locked by all the members of the list, and if 
   neither, the sheet is seriously locked by that person.
LOCK-SHEET m (SHEET) . BODY
   Wait for the lock on SHEET, grab it, do BODY, and release the lock.
OLD-SCREEN-ARRAY iv SHEET
   When typeout on SHEET gets disallowed, SCREEN-ARRAY gets copied
   to OLD-SCREEN-ARRAY to avoid having to cons it up again when
   typeout is again allowed.
PREPARE-SHEET m (SHEET) . BODY ?
   Make sure that this sheet can get the lock (?) by calling
   SHEET-PREPARE-SHEET-INTERNAL if necessary, and then do BODY.
PREPARED-SHEET v ?
RECT-BOTTOM m R
   Same as FIFTH, the bottom edge of a rectangle
RECT-LEFT m R
   Same as SECOND, the left edge of a rectangle
RECT-NOT-OVERLAP-RECT-P m R1 R2
   Returns NIL only if the rectangle R1 intersects the rectangle
   R2.   
RECT-RIGHT m R
   Same as FOURTH, the right edge of a rectangle
RECT-SOURCE m R
   Same as FIRST, the source of a rectangle
RECT-TOP m R
   Same as THIRD, the top edge of a rectangle
RECT-WITHIN-RECT-P m R1 R2
   Returns NIL only if the rectangle R1 does not lie completely within
   the rectangle R2.
rectangle
   Rectangular areas on the screen are sometimes represented as
   5-lists, whose members are the source, left edge, top edge,
   right edge, and bottom edge of the rectangle.
REDIRECT-ARRAY m &REST ARGS ?
   "Redirects a screen array," but cannot be understood until
   SI:CHANGE-INDIRECT-ARRAY is.
resource
   We often come across classes of objects that are expensive to make
   but reusable.  The way to solve this problem is to keep all the 
   presently unused ones on a list, allocate and deallocate them by
   popping and pushing the list, and only create a new one when there
   are none available.

   A resource is a symbol whose binding is such a list and whose function
   is a manufacturer for such an item.  cf. DEFRESOURCE, ALLOCATE-RESOURCE,
   DEALLOCATE-RESOURCE, RESOURCE.
RESOURCE m (NAME VAR) . BODY
   Allocate a NAME resource (see resource) and execute BODY with
   VAR bound to it.  Even if BODY blows up, deallocate the resource
   when finished.
SCREEN fl [SHEET]
SCREEN-ARRAY iv SHEET
   If typeout on SHEET is allowed, SCREEN-ARRAY is where it happens.
   If typeout is not allowed, SCREEN-ARRAY will be NIL.
SCREEN-MANAGER-QUEUE v
   Used to queue up screen management operations that occur inside
   DELAYING-SCREEN-MANAGEMENT forms.  See DELAYING-SCREEN-MANAGEMENT.
SCREEN-MANAGER-TOP-LEVEL v
   This is set to T usually, but bound to NIL inside DELAYING-SCREEN-
   MANAGEMENT forms.  See DELAYING-SCREEN-MANAGEMENT.
SHEET fl
SHEET-CONSING m &REST BODY
   Do BODY while consing by default in the sheet area.
SHEET-END-LINE-FLAG m &OPTIONAL SHEET
   Cursor is to the right of the right limit on SHEET.
SHEET-EXCEPTIONS m &OPTIONAL SHEET
   Reasons why typeout can't happen on SHEET
SHEET-FORCE-ACCESS m (SHEET DONT-PREPARE-SHEET) . BODY ?
SHEET-INSIDE-BOTTOM m &OPTIONAL SHEET
   Bottom inside edge of SHEET
SHEET-INSIDE-HEIGHT m &OPTIONAL SHEET
   Distance between horizontal inside edges of SHEET
SHEET-INSIDE-LEFT m &OPTIONAL SHEET
   Left inside edge of SHEET
SHEET-INSIDE-RIGHT m &OPTIONAL SHEET
   Right inside edge of SHEET
SHEET-INSIDE-TOP m &OPTIONAL SHEET
   Top inside edge of SHEET
SHEET-INSIDE-WIDTH m &OPTIONAL SHEET
   Distance between vertical inside edges of SHEET
SHEET-MORE-FLAG m &OPTIONAL SHEET
   More processing needs to happen on SHEET
SHEET-OLD-SCREEN-ARRAY am
SHEET-OUTPUT-HELD-P m &OPTIONAL SHEET
   Output hold flag is on or there is a temporary lock
SHEET-OUTPUT-HOLD-FLAG m &OPTIONAL SHEET
   Output may not happen on SHEET; next time someone tries, they
   will go blocked
SHEET-RIGHT-MARGIN-CHARACTER-FLAG m &OPTIONAL SHEET
   Exclamation point used on SHEET to indicate line wraparound
SHEET-SCREEN-ARRAY am
SHEET-SUPERIOR-SCREEN-ARRAY m &OPTIONAL SHEET
   SHEET's SUPERIOR's screen array, whether SHEET is exposed or not
SHEET-TEMPORARY-BIT-ARRAY am
SHEET-TEMPORARY-P m &OPTIONAL SHEET
   Does SHEET have a temporary bit array?
SHEET-TRUNCATE-LINE-OUT m &OPTIONAL SHEET
   Just truncate on SHEET rather than wrapping around
SHEET-X f 
   Same as SHEET-X-OFFSET
SHEET-Y f
   Same as SHEET-Y-OFFSET
TEMPORARY-BIT-ARRAY i SHEET
   An array of bits of the same size as SHEET, designed to preserve
   what was under SHEET when it was last exposed, so that it can
   be restored when SHEET is deexposed
WITH-MOUSE-GRABBED m &REST BODY
   *****
WITHOUT-SCREEN-MANAGEMENT m &REST BODY
   Sometimes you can determine that a sequence of operations will
   not require screen management if it is completed successfully.
   This macro enables one to suppress well-intentioned but mis-
   guided screen management during the execution of BODY.  If BODY
   completes successfully, the screen management operations that
   would have occurred in the meantime are flushed.  However, if
   BODY blows up, the queued screen management operations get done
   in order to be safe.
WHO-LINE-ITEM s
   A field of the who line
WHO-LINE-ITEM-FUNCTION sm WHO-LINE-ITEM ?
WHO-LINE-ITEM-LEFT sm WHO-LINE-ITEM ?
WHO-LINE-ITEM-RIGHT sm WHO-LINE-ITEM ?
WHO-LINE-ITEM-STATE sm WHO-LINE-ITEM ?
WHO-LINE-LIST v
   A list of WHO-LINE-ITEMs (qv.) to be displayed on the who line
WHO-LINE-RUN-LIGHT-LOC v
   The address of the run light under the who line
WHO-LINE-RUN-STATE v
   The current state (RUN, STOP, TYI, etc.)
WHO-LINE-WINDOW v
   Sheet used for writing the who line
WINDOW-CALL m (WINDOW FINAL-ACTION) . BODY
   Select WINDOW, do the BODY, and deselect the WINDOW.  Then if 
   there is a FINAL-ACTION, send it to the WINDOW.  The BODY is
   unwind-protected so that the deselection and FINAL-ACTION will
   always take place even if something goes wrong.
WINDOW-PUSH f WINDOW NEW-TYPE &REST INIT-PAIRS
   *****