The bare cross-reference to an equation, without the Eq. in front of it: {{eqref|00fC1}} prints \eqref{eq:00fC1}, which MathJax renders as the equation's number in parentheses. For the usual thing — Eq. (3) — use [[Template:Eq|{{eq}}]], which is built on this and also does the plural. This one is for a sentence that supplies its own wording: compare with \eqref{eq:00fC1} above.

The tag is an Anno Fabri tag, base62 and case-sensitive, taken from the equation's \label{eq:…}.

Since 1 September 2026 it goes through Module:Eq, which is what makes it work from another page: there the number cannot be MathJax's, MathJax numbering one page at a time, so it is counted out of that page's wikitext while this page is parsed, and what comes out is an ordinary link to the equation. On the page holding the equation nothing changes — it is still the \eqref above. Say which page with |in=August (2026); with nothing said, the tag's own month page is where it looks.