In English, the term ruby refers to small text set above the main text (in horizontal writing) or to the right of the main text (in vertical writing). From Wikipedia:
Ruby characters (ルビ) are small, annotative glosses that can be placed above or to the right of a Chinese character when writing languages with logographic characters such as Chinese or Japanese to show the pronunciation. Typically called just ruby or rubi, such annotations are used as pronunciation guides for characters that are likely to be unfamiliar to the reader.
As I understand it, this is mainly a typography term, and it's likely that many speakers are unfamiliar with it, but web developers probably know the term due to the HTML <ruby> tag. Students of Japanese are more likely to know furigana than ruby.
In Japanese, although ルビ is used, I think that 振{ふ}り仮名{がな} is a much more common word. Taken literally, 振り仮名 appears to refer specifically to kana, as in hiragana or katakana. That would make ルビ a more general term, including small kanji or rōmaji used as ruby.
In fact, I've seen the term 振{ふ}り漢字{かんじ} used on occasion, in contrast to 振{ふ}り仮名{がな}:
kanji printed as ruby, usually to explain kana
My feeling is that taken strictly, 振{ふ}り仮名{がな} should only refer to kana used as ruby, not to kanji or rōmaji. But I'm not sure if that reflects actual usage, so I've decided to ask this question:
Is it common to use the term 振{ふ}り仮名{がな} for ruby text, even when the characters aren't kana?
(And if so, would that be considered sloppy usage, or would it be perfectly normal / acceptable?)
