In the directory /usr/share/doc/packages/pam of your installed system, find the following additional documentation:
In the top level of this directory, there are some general README files. The subdirectory modules holds README files about the available PAM modules.
This document includes everything that a system administrator should know about PAM. It discusses a range of topics, from the syntax of configuration files to the security aspects of PAM. The document is available as a PDF file, in HTML format, and as plain text.
This document summarizes the topic from the developer's point of view, with information about how to write standard-compliant PAM modules. It is available as a PDF file, in HTML format, and as plain text.
This document includes everything needed by an application developer who wants to use the PAM libraries. It is available as a PDF file, in HTML format, and as plain text.
Thorsten Kukuk has developed a number of PAM modules for SUSE LINUX and made available some information about them at: http://www.suse.de/~kukuk/pam/