The final fact about the Guru Granth Sahib is the one that governs every other. In 1708, Guru Gobind Singh ended the succession of human Gurus and invested the scripture itself with that authority. The volume is the Guru, and has been for more than three centuries.
What follows is not a set of respectful customs added to a book. It is the treatment appropriate to a living Guru: installed on a raised seat under a canopy rather than shelved, attended, fanned with a whisk as a sovereign is attended, taken at night to a room of its own and brought out in the morning. Those in its presence uncover their feet and cover their heads. Its pages are called limbs. Marriages are conducted by circling it. Community decisions are taken before it.
For a reference work this sets an obligation and a boundary, and both are worth stating for the reader rather than being quietly observed. The obligation is accuracy, because errors of fact about the structure, the compilation and the history of the volume are errors about a Guru. The boundary is that the atlas describes and does not perform: it does not reproduce the text, does not paraphrase hymns closely enough to substitute for them, and does not set out the tradition's practices as procedures a reader can follow.
The thirty-one rag sections recorded here are a description of how a volume is arranged. They are not the volume, and no catalogue entry is.