You are looking at the documentation for the 1.3 version of the Apache HTTP Server, which is no longer maintained, and has been declared "end of life". If you are in fact still using the 1.3 version, please consider upgrading. The current version of the server is 2.4.
Each Apache directive available in the standard Apache distribution is listed here. They are described using a consistent format, and there is a dictionary of the terms used in their descriptions available.