The label (e.g. "[9]") of a <ref> tag normally (on en.wiki anyway) if clicked will scroll to the reference text, and if hovered over will either pop up a box with the reference text (if the reference is offscreen) or highlight the reference text (if the reference is onscreen). However if the <ref> tag has a name parameter with any of various character sequences, such as %20, then none of these responses will happen. This is a problem for a reader wanting to see the reference information.
Known problem sequences
Some of these are more frequent than you might expect. There likely are other character sequences that fail in the same way. For example, the %c8%98 represents a Latin letter with diacritical marks, and there are lots of such letters. The basic problem seems to be that the html generated uses different identifiers for the link to the reference and the target. Apparently the name value is used to build the identifier, but the identifier is built in two different ways, one for the link and one for the target. Seems like a sure recipe for bugs.
Note that if one has accidentally used such a name value for a ref tag, it will not be apparent that there is a problem. No one goes around hovering over every reference label in an article. Also, some automated or "semi-automated" edits may change a ref name in a way that starts the ref label failing in this way. All the more reason the software should generate the html identifier in one place and not two so that mismatches won't occur.
List of steps to reproduce:
- Add lines like these to a page:
The mouse.<ref name="A - Z"> Animals A to Z </ref> == References == * <references />
- Save the page
- Hover the cursor over the reference label which follows "The mouse.".
What happens?:
- Nothing
What should have happened instead?:
- The reference line with "Animals A to Z" should be highlighted (or a popup with that text shown).