The most important fact about the Guru Granth Sahib is not in its contents. In 1708 Guru Gobind Singh, the tenth in the succession, ended the line of human Gurus by investing the scripture itself with that authority. There has been no human Guru since, and the volume is not a book about the Gurus but the Guru.
Everything about how it is handled follows from that. It is installed rather than shelved, placed on a raised seat under a canopy, attended, and taken at night to a room of its own. A person entering its presence uncovers their feet and covers their head. A whisk is passed over it in the manner of attendance on a sovereign. Congregational decisions are taken in its presence. Its pages are limbs.
For a reference work this creates an obligation of description rather than a difficulty. Facts about the volume, its structure, its compilation, its measures, its languages and its history are the atlas's to record, and it records them. The expression of its contents is not the atlas's to reproduce, and it is not reproduced.
The distinction between the two is easy to state and easy to lose. Describing what a section contains is a fact. Quoting the section at length, paraphrasing its hymns closely enough to substitute for them, or presenting the tradition's practice as something a reader can pick up and perform, is not description. This atlas keeps to the first side of that line for every living tradition, and it keeps to it here with particular care.