§

The section sign is an S folded over itself — signum sectionis — and it addresses divisions of text: § 2 reads “section two”. In legal citation it is official syntax.

Doubled, §§ 2–3, it addresses a range of sections. The entity is §; between the sign and the number goes a no-break space, so the § is never orphaned at the end of a line.

Wrong:  as per sec. 2 of art. 5
Right:  as per § 2 of art. 5