<!-- Creator : groff version 1.21 --> <!-- CreationDate: Wed Feb 9 07:50:05 2011 --> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta name="generator" content="groff -Thtml, see www.gnu.org"> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <meta name="Content-Style" content="text/css"> <style type="text/css"> p { margin-top: 0; margin-bottom: 0; vertical-align: top } pre { margin-top: 0; margin-bottom: 0; vertical-align: top } table { margin-top: 0; margin-bottom: 0; vertical-align: top } h1 { text-align: center } </style> <title>pic-1.html</title> </head> <hr> <a href="http://validator.w3.org/check?uri=referer"><img src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01 Transitional" height="31" width="88"></a> [ <a href="pic-2.html">next</a> | <a href="pic.html">top</a> ] <hr> <h2>1. Introduction to PIC <a name="1. Introduction to PIC"></a> </h2> <h3>1.1. Why PIC? <a name="1.1. Why PIC?"></a> </h3> <p style="margin-top: 1em">The <b>pic</b> language provides an easy way to write procedural box-and-arrow diagrams to be included in <b>troff</b> documents. The language is sufficiently flexible to be quite useful for state charts, Petri-net diagrams, flow charts, simple circuit schematics, jumper layouts, and other kinds of illustration involving repetitive uses of simple geometric forms and splines. Because these descriptions are procedural and object-based, they are both compact and easy to modify.</p> <p style="margin-top: 1em">The phrase “GNU pic” may refer to either of two <b>pic</b> implementations distributed by the Free Software Foundation and intended to accept the same input language. The <i>gpic</i>(1) implementation is for use with the <i>groff</i>(1) implementation of <b>troff</b>. The <i>pic2plot</i>(1) implementation runs standalone and is part of the <b>plotutils</b> package. Because both implementations are widely available in source form for free, they are good bets for writing very portable documentation.</p> <h3>1.2. PIC Versions <a name="1.2. PIC Versions"></a> </h3> <p style="margin-top: 1em">The original 1984 pre-<i>ditroff</i>(1) version of <b>pic</b> is long obsolete. The rewritten 1991 version is still available as part of the Documenter’s Work Bench module of System V.</p> <p style="margin-top: 1em">Where differences between Documenter’s Work Bench (1991) <b>pic</b> and GNU <b>pic</b> need to be described, original <b>pic</b> is referred to as “DWB pic”. Details on the history of the program are given at the end of this document.</p> <p style="margin-top: 1em">The <b>pic2plot</b> program does not require the rest of the <i>groff</i>(1) toolchain to render graphics. It can display <b>pic</b> diagrams in a X window, or generate output plots in a large number of other formats. These formats include: PNG, PBM, PGM, PPM, GIF, SVG, Adobe Illustrator format, idraw-editable Postscript, the WebCGM format for Web-based vector graphics, the format used by the <b>xfig</b> drawing editor, the Hewlett-Packard PCL 5 printer language, the Hewlett-Packard Graphics Language (by default, HP-GL/2), the ReGIS (remote graphics instruction set) format developed by DEC, Tektronix format, and device-independent GNU graphics metafile format.</p> <p style="margin-top: 1em">In this document, <i>gpic</i>(1) and <i>pic2plot</i>(1) extensions are marked as such.</p> <hr> <a href="http://validator.w3.org/check?uri=referer"><img src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01 Transitional" height="31" width="88"></a> [ <a href="pic-2.html">next</a> | <a href="pic.html">top</a> ] <hr>