6.2. The lang.encoding/ directories

These directories contain the documents themselves. The documentation is split into up to three more categories at this level, indicated by the different directory names.

articles	Documentation marked up as a DocBook <article> (or equivalent). Reasonably short, and broken up into sections. Normally only available as one HTML file.
books	Documentation marked up as a DocBook <book> (or equivalent). Book length, and broken up in to chapters. Normally available as both one large HTML file (for people with fast connections, or who want to print it easily from a browser) and as a collection of linked, smaller files.
man	For translations of the system manual pages. This directory will contain one or more mann directories, corresponding to the sections that have been translated.

Not every lang.encoding directory will contain all of these directories. It depends on how much translation has been accomplished by that translation team.