PDF Output

PDF (Portable Document Format) is a format designed by Adobe in early 1990. This page describes some expriments related to PDF files.

PDF and Postscript share several features:

• Text files
• Same graphical model (shapes, attributes, coordinate transforms)
• Language based on a stack

However, they also have important differences. Postscript is a complete language with variables, conditional execution, loops and procedure definitions. For this reason, it is difficult to extract pages without executing the whole PS file. PDF, on the other hand, is purely descriptive. It also has a table of contents (cross-reference table) which lets a PDF reader jump directly to a page or a resource without parsing the whole file.

The table of contents makes manual experimentation with a text editor difficult, because offsets in the file must be updated every time the length of the page contents changes. This task is better left to a program, such as pdfwrapper which lets you play online.