Should the furigana go above the whole word or individual kanji?


I've seen both styles used, basically:

> A = 家内{かない}  
>  B = 家{か}内{ない}

I can see pros and cons for both styles. The rendering of A is probably better
and there are words for which it may be difficult to say which character is
responsible for which sound. On the other hand, B provides more information
about the sound of individual kanji.

My questions therefore are:

  1. Are there objective criteria to prefer one style over the other?
  2. Is one of the two styles considered in some way "official"?
  3. Which of the two is actually more widely used?




In DTP jargon, per-word rubies (A) are called **グループルビ** (group-ruby), and
per-kanji rubies (B) are called **モノルビ** (mono-ruby). There's also an
intermediate convention called **熟語ルビ** (jukugo-ruby).

[![Samples](https://i.stack.imgur.com/TNNz3.png)](https://i.stack.imgur.com/TNNz3.png)

* * *

>   1. Are there objective criteria to prefer one style over the other?
>

Basically, prefer mono-ruby (B) for ordinary compounds where there's one-to-
one correspondence between a kanji and a reading (e.g., 土曜日 = ど/よう/び). Use
group-ruby (A) for jukujikun (i.e., 大人, 明日) and those [unconventional/creative
rubies](https://japanese.stackexchange.com/q/29431/5010).

As an exception, I personally prefer group-ruby on this site because mono-ruby
can severely hurt searchability. Typing `家​【か】内​【ない】` produces 家【か】内【ない】, but
it splits the word and makes it impossible to search.

When three or more kana are assigned to one kanji (e.g., 胃袋 = い/ぶくろ, 侍魂 =
さむらい/だましい, 桜木町 = さくら/ぎ/ちょう), we have to consider spacing and **overhanging**
as well, and there are many small rules around them. Please read [this
"Note"](https://www.w3.org/TR/jlreq/#adjustments_of_ruby_with_length_longer_than_that_of_the_base_characters)
by W3C if you are interested. Overhanging is not supported by the furigana
extension of this site, MS Word, or the `<ruby>` tag of modern browsers. It's
supported by professional-use DTP software like Adobe InDesign.

>   2. Is one of the two styles considered in some way "official"?
>   3. Which of the two is actually more widely used?
>

They are both common and have their own use cases. I can say mono-ruby is
generally preferred in very simple cases such as 家内, but there are various
house rules depending on the publisher for tricky cases. The W3C's "Note" is
based on [JIS (Japan Industrial Standard) X
4051](https://ja.wikipedia.org/wiki/JIS_X_4051). The document by W3C should
serve as a general consensus.




In DTP jargon, per-word rubies (A) are called **グループルビ** (group-ruby), and
per-kanji rubies (B) are called **モノルビ** (mono-ruby). There's also an
intermediate convention called **熟語ルビ** (jukugo-ruby).

[![Samples](https://i.stack.imgur.com/TNNz3.png)](https://i.stack.imgur.com/TNNz3.png)

* * *

>   1. Are there objective criteria to prefer one style over the other?
>

Basically, prefer mono-ruby (B) for ordinary compounds where there's one-to-
one correspondence between a kanji and a reading (e.g., 土曜日 = ど/よう/び). Use
group-ruby (A) for jukujikun (i.e., 大人, 明日) and those [unconventional/creative
rubies](https://japanese.stackexchange.com/q/29431/5010).

As an exception, I personally prefer group-ruby on this site because mono-ruby
can severely hurt searchability. Typing `家​【か】内​【ない】` produces 家【か】内【ない】, but
it splits the word and makes it impossible to search.

When three or more kana are assigned to one kanji (e.g., 胃袋 = い/ぶくろ, 侍魂 =
さむらい/だましい, 桜木町 = さくら/ぎ/ちょう), we have to consider spacing and **overhanging**
as well, and there are many small rules around them. Please read [this
"Note"](https://www.w3.org/TR/jlreq/#adjustments_of_ruby_with_length_longer_than_that_of_the_base_characters)
by W3C if you are interested. Overhanging is not supported by the furigana
extension of this site, MS Word, or the `<ruby>` tag of modern browsers. It's
supported by professional-use DTP software like Adobe InDesign.

>   2. Is one of the two styles considered in some way "official"?
>   3. Which of the two is actually more widely used?
>

They are both common and have their own use cases. I can say mono-ruby is
generally preferred in very simple cases such as 家内, but there are various
house rules depending on the publisher for tricky cases. The W3C's "Note" is
based on [JIS (Japan Industrial Standard) X
4051](https://ja.wikipedia.org/wiki/JIS_X_4051). The document by W3C should
serve as a general consensus.

