For most of its history the verse was restricted, and the restriction is a live subject rather than a historical footnote.
Recitation belonged to the upanayana, the initiation at which a boy of the three upper varnas received the sacred thread and was taught the verse by his teacher. That initiation is what the term twice-born names. Shudras and, in the dominant classical position, women were excluded, and the exclusion was enforced by law codes and by social sanction rather than merely recommended.
The position changed substantially in the nineteenth and twentieth centuries and it changed from inside. The Arya Samaj, founded in 1875, made universal access to Vedic recitation a central plank and initiated women and people of all castes. Reformist and neo-Vedantic movements followed. The verse is now recited publicly, taught to anyone, sold on recordings, and used at the opening of secular events in India. A conservative minority of orthodox lineages maintain the older restriction, and disputes about it recur.
This atlas gives the verse in full, and the reason is worth stating plainly rather than left implicit: the restriction is contested within the tradition, the majority position now rejects it, and the text is published in every edition of the Rig Veda in print. That is different from the cases in this collection where a lineage still withholds material and where nothing is supplied.
The verse is also held here as a hymn in its own right, because it is one, a Rig Vedic hymn verse before it was ever a formula, and the two treatments are deliberately kept apart.