Re: kanjidic2 katakana "kun" readings

[Nils Roland Barth <jmdict.nbarth@********>]

Stuart:
>> [... Why are some kun readings in katakana? ...]
>>   ja_kun - the "kun" Japanese reading of the kanji, usually in hiragana.

Jim:
> [...These are Meiji-era kokuji. ...]

Thanks for raising this Stuart, and for the explanation Jim.
This puzzled me too when I learned about it (for 頁 ページ page),
so I looked into it and wrote it up here:
http://en.wiktionary.org/wiki/Appendix:Single_character_gairaigo
http://en.wikipedia.org/wiki/Ateji#Single-character_loan_words

In brief:
They’re kun readings because the character is being used for *meaning*,
and they’re katakana because the word is gairaigo (a modern borrowing).

Normally we think of
“on = Chinese (Sino-Japanese), kun = (native) Japanese,
 gairaigo = separate category”
but strictly speaking, “on = sound, kun = meaning”, and as
the borrowed word is not connected with an existing reading,
it’s “kun” by this classification.

The everyday examples are:
頁 ページ pēji "page"
零 ゼロ zero "zero"
打 ダース dāsu "dozen"

Beyond that it gets obscure quickly, as Jim notes;
a 60-something literature teacher was completely baffled by 粁,
for instance.
(There are many more examples in refs above.)

Also, note that:
缶（罐） カン kan "can, metal tin"
is actually a single kanji ateji, since カン was an exiting
(on) reading for the character, though the use as gairaigo
is newer. (Hence this is not a kun reading.)

>> 志 (kun): シリング
> 
> This one has a genuine On reading of シ as well.

…which is related to シ-リング – per 広辞苑：
(5) シリング。イギリスの貨幣単位shillingの音訳「志令」の略。

This character is also amusing for having one of the longest
(old Japanese) kun'yomi in the jōyō set,
こころざし (from 心差し こころ-さし).

cheers,
  ~nils