Technologies determine colors used in Ptolemy facets
as well as the connector style.  The technology you use
is determined by X resource vem*technology, which by
default will be set to ~ptolemy/lib/technology.
If your environment variable PIGIBW is set, the technology used
will be in ~ptolemy/lib/tech4dump.  This technology is designed
for creating screendumps that can be usefully printed in black and white.
Another useful technology is in ~ptolemy/lib/tech4colorPrint, which
is tuned for color printers.

All technologies are stored in ~ptolemy/lib.
Each technology is in a subdirectory.  For example,
in ~ptolemy/lib/technology, there are two subdirectories
of interest: gabriel and ptolemy.  The "gabriel" directory
defines a technology used to read facets from Ptolemy's predecessor,
called gabriel.  The ptolemy facets all use the technology in the
ptolemy directory.

Suppose you want to make all whites in the ptolemy technology
black instead.  You can do the following:
(Don't do this in our master copy, or you could become very
unpopular).

cd ~ptolemy/lib/technology/ptolemy/tap.views

Then edit a file called schematic.pat changing the relative
intensities of the red, green, and blue in each of the "layers".
For instance, your could change:

  (figureGroupDefault whiteSolid
      (userData priority 5)
      (width -2)
      (color 1000 1000 1000)
      (fillPattern 1 1 "1")
  )

to be

  (figureGroupDefault whiteSolid
      (userData priority 5)
      (width -2)
      (color 0 0 0)
      (fillPattern 1 1 "1")
  )

which will be black.  Note that the layer will still be called "whiteSolid".

Then run pat2tap, an octtools program, to generate the "tap" file used
by Ptolemy:

cd ~ptolemy/lib/technology/ptolemy
pat2tap

The following dialog will ensue:
(you enter the stuff after the ":")
	VEM Pattern Filename: tap.views/schematic.pat
	Technology name in pattern file [physical]: schematic
	TAP root directory [$OCTTOOLS/tech]: ~ptolemy/lib/technology
	Output technology name [scmos]: ptolemy
	Output view name [schematic]: 
	Specify X host and display [no]: 
	Output display type [MIT X Consortium]: GENERIC-COLOR
	Color output device [yes]: 
	Loaded technology 'schematic' from file 'tap.views/schematic.pat'
	Saved results into ~ptolemy/lib/technology/ptolemy/tap.views:schematic:contents


You should probably also update the technology for black and white monitors:

pat2tap
	VEM Pattern Filename: tap.views/schematic.bw.pat
	Technology name in pattern file [physical]: schematic
	TAP root directory [$OCTTOOLS/tech]: ~ptolemy/lib/technology
	Output technology name [scmos]: ptolemy
	Output view name [schematic]: 
	Specify X host and display [no]: 
	Output display type [MIT X Consortium]: PostScript-BW
	Color output device [yes]: no
	Loaded technology 'schematic' from file 'tap.views/schematic.bw.pat'
	Saved results into ~ptolemy/lib/technology/ptolemy/tap.views:schematic:contents

Unfortunately, although this creates a working technology, it has some
artifacts.  We have provided a program to clean these up:

~ptolemy/lib/technology/ptolemy/cleantap/cleantap

	Enter cell name of tech facet:~ptolemy/lib/technology/ptolemy/tap.views
