This directory contains supplementary documentation on GNU libplot, the
drawing library on which the plotting utilities graph, plot, and tek2plot
are based.

    ./colors.txt: A listing of the color names recognized by libplot,
  		  and hence by each of the three plotting utilities.  
  		  A 24-bit RGB representation for each color is given.

  		  For example, you may use the command

			graph --frame-color chocolate

		  because "chocolate" is one of the listed color names.
		  In the 24-bit RGB scheme, "chocolate" means (210,105,30).
		  The strength of each of R (red), G (green), and B (blue)
		  is represented as an 8-bit quantity, i.e., an integer
		  in the range 0..255.

The following files are relevant to the 22 Hershey fonts built into GNU
libplot, and accessible to the plotting utilities.

    ./demo-page: A sample page, in portable GNU metafile format, 
		 illustrating many of the Hershey fonts.  The page is 
		 taken from  Allen Hershey's 1972 article in 
		 Computer Graphics and Image Processing 
		 (vol. 1, no. 4, pp. 373-385). You would use the `plot' 
		 utility to display the page.
		 For example, do `plot -T X demo-page' to display the
		 page on an X Window System display,
		 `plot -T ps demo-page > demo-page.ps' to prepare a
		 Postscript version of the page, 
		 `plot -T cgm demo-page > demo-page.cgm' to prepare a
		 WebCGM version of the page, 
		 `plot -T fig demo-page > demo-page.fig' to prepare a
		 version of the page that can be edited with the `xfig'
		 drawing editor, etc.
	
    ./h-demo.c:  The program that was used to generate `./demo-page'.
		 You may compile this program and link it with GNU libplot 
		 (the instructions are at the head of the file).  It will
		 send the sample page to standard output, in portable 
		 GNU metafile format.  This program illustrates how to 
		 write a C program that invokes GNU libplot functions.

    ./h-fonts: Excerpts from Allen Hershey's `Calligraphy for Computers',
	explaining the origin of the Hershey fonts.

When specifying to the plotting utilities that a Hershey font should be
used, you would usually specify it by name, e.g., `graph --font-name
HersheyGothicEnglish'.  However, the Hershey fonts are assembled from a
large collection of glyphs (`Hershey glyphs'), including many
symbols in addition to occidental and Japanese characters.  If the current
font is a Hershey font, you may access any glyph by its number, even if it
is not a character in the font. For example, the command

	graph --font-name HersheyGothic-English -L '\#H0745\#H0745'

would label the graph being drawn with a title line consisting of
two fleurs-de-lys.  That is because the fleur-de-lys is Hershey glyph #745.

    ./h-glyphs: A breakdown of the `occidental' Hershey glyphs,
        by number.  Includes an extensive comparison with earlier
	(pre-GNU) distributions of the Hershey glyphs, and an explanation
	of how the glyph array was assembled.
    
    ./hershey.bib: A bibliography, in BibTeX format, of publications
        dealing with the Hershey glyphs and with Allen Hershey's system for
        scientific typography, which was designed to use them.  Most cited
        items are technical reports that are available from the
        U.S. National Technical Information Service (+1 703 487 4650).
        Stock numbers are given.
    
    ./kana.doc: The encodings used for the Hershey Hiragana and Katakana
        (syllabic Japanese characters).  These are part of the HersheyEUC
	font, but may also be accessed by number.
    
    ./kanji.doc: The encoding of the 603 available Japanese Kanji
        (ideographic characters), and their meaning.  These are part of the
	HersheyEUC font, but may also be accessed by number.
