1. Introduction

Welcome to the PostScript Language Reference Guide - your comprehensive resource for mastering PostScript programming.

2. What is PostScript?

PostScript is a stack-based, interpreted programming language created by Adobe Systems in 1984. It revolutionized desktop publishing by providing a device-independent way to describe pages for printing and display.

2.1. Key Characteristics

Stack-Based Execution

PostScript uses a last-in, first-out (LIFO) stack for all operations:

3 4 add    % Push 3, push 4, add them → 7
5 mul      % Multiply by 5 → 35

Concatenative Language

Operations are composed by concatenation - no explicit function calls or variable assignments needed:

/square { dup mul } def
5 square   % Result: 25

Device Independent

The same PostScript program produces identical output on any PostScript-compatible device, from laser printers to imagesetters.

2.2. Core Concepts

The Operand Stack

Central to PostScript - all data flows through the stack:

10 20      % Stack: 10 20
add        % Stack: 30
2 div      % Stack: 15

Dictionaries

PostScript’s namespaces - mapping names to values:

/x 100 def      % Define x as 100
/y 200 def      % Define y as 200
x y add         % Use them: 300

Procedures

Reusable code blocks:

/drawBox {
  0 0 moveto
  100 0 lineto
  100 100 lineto
  0 100 lineto
  closepath
} def

Graphics Model

Powerful vector graphics based on paths:

newpath
100 100 moveto    % Start point
200 150 lineto    % Draw line
stroke            % Render the path

3. Why Learn PostScript?

Professional Publishing

  • Industry standard for prepress and printing

  • Precise control over typography and layout

  • Support for complex color management

PDF Foundation

  • PDF is derived from PostScript

  • Understanding PostScript helps with PDF manipulation

  • Many PDF tools use PostScript internally

Programmatic Graphics

  • Generate graphics algorithmically

  • Create custom visual effects

  • Automate document production

Legacy Systems

  • Many existing systems use PostScript

  • Understanding enables maintenance and updates

  • Integration with modern workflows

4. Getting Started

4.1. Your First Program 

%!PS-Adobe-3.0
/Helvetica findfont 12 scalefont setfont
100 700 moveto
(Hello, PostScript!) show
showpage

4.2. Learning Path

  1. Start with basics - Stack Operations

  2. Learn arithmetic - Math Commands

  3. Understand data - Arrays and Strings

  4. Master dictionaries - Dictionary Operations

  5. Control flow - Conditionals and Loops

  6. Graphics - Graphics State and Path Construction

5. About This Guide

This reference provides:

  • Complete operator reference - All PostScript commands documented

  • Practical examples - Real-world code samples

  • Common pitfalls - Warnings about gotchas

  • Performance tips - Optimization guidance

  • Level indicators - Which version introduced each feature

  • By Category - Browse commands by functional area

  • Alphabetically - Find commands by name

  • By Level - See what each PostScript version offers

  • Examples - Learn from working code

6. See Also