I know about the "standard" special katakana, like ファ fa, ディ di, ヴ vu, etc. However, I keep running into others I can't find on any list, including the ones in What special kana are used to write foreign words?

For example, on this Wikipedia page, one character has the name:

Quark (クォーク Kwōku)

I've never seen クォ kwo in any katakana list.

Another example is フュ fyu, as in the new movie X-MEN: フューチャー&パスト.

So, what are all the "non-standard" katakana in regular use?

I know about the "standard" special katakana, like ファ fa, ディ di, ヴ vu, etc. However, I keep running into others I can't find on any list, including the ones in What special kana are used to write foreign words?

For example, on this Wikipedia page, one character has the name:

Quark (クォーク Kwōku)

I've never seen クォ kwo in any katakana list.

Another example is フュ fyu, as in the new movie X-MEN: フューチャー&パスト.

So, what are all the "non-standard" katakana in regular use?

I know about the "standard" special katakana, like ファ fa, ディ di, ヴ vu, etc. However, I keep running into others that aren't found on any katakana lists I've ever seen, including the lists in What special kana are used to write foreign words?

For example, on this Wikipedia page, one of the characters' name is listed as:

Quark (クォーク Kuōku)

I asked a Japanese speaker why kuo is written クォ and not クオ, and he said "The correct romanization for クォ is kwo." I've never seen クォ in any katakana list.

Another example I haven't seen anywhere is フュ fyu, seen in the new movie X-MEN: フューチャー&パスト.

So, what are all the non-standard katakana in regular use?

I know about the "standard" special katakana, like ファ fa, ディ di, ヴ vu, etc. However, I keep running into others I can't find on any list, including the ones in What special kana are used to write foreign words?

For example, on this Wikipedia page, one character has the name:

Quark (クォーク Kwōku)

I've never seen クォ kwo in any katakana list.

Another example is フュ fyu, as in the new movie X-MEN: フューチャー&パスト.

So, what are all the "non-standard" katakana in regular use?

I know about the "special" katakana that are typically taught, like ファ fa, ディ di, etc. However, I keep running into others that aren't found on any katakana lists I've ever seen, including the one in this question.

For example, on this Wikipedia page, one of the characters' name is listed as:

Quark (クォーク Kuōku)

I asked my friend who is fluent in Japanese why kuo is written クォ and not クオ, and he said "The correct romanization for クォ is kwo." I've never seen クォ in any katakana list.

Another example I haven't seen anywhere is フュ fyu, seen in the new movie X-MEN: フューチャー&パスト.

So, what other non-standard katakana are used regularly?

I know about the "standard" special katakana, like ファ fa, ディ di, ヴ vu, etc. However, I keep running into others that aren't found on any katakana lists I've ever seen, including the lists in What special kana are used to write foreign words?

For example, on this Wikipedia page, one of the characters' name is listed as:

Quark (クォーク Kuōku)

I asked a Japanese speaker why kuo is written クォ and not クオ, and he said "The correct romanization for クォ is kwo." I've never seen クォ in any katakana list.

Another example I haven't seen anywhere is フュ fyu, seen in the new movie X-MEN: フューチャー&パスト.

So, what are all the non-standard katakana in regular use?