How to explain the katakana spelling for a foreign name with a long vowel?


Apologies in advance if the title of my question is unclear. Please edit if
you can think of a better way to phrase it!

From time to time, you need to explain how a foreign name is spelled in
katakana. Example: The first name `Bart` is commonly written as `バート`.

Imagine that you are applying for a credit card on the telephone. What is the
correct way to explain this katakana spelling?

Example: `名{な}（ファーストネーム）はバートです。バ、（？）、ト。`

How to explain that the first katanana character (`バ`) has a long vowel?

Related topic: How to explain a small vowel? Example: `Tio` might be written
as `ティオ`. How to explain the small `イ`? Normally, I would say `テ、小{ちい}さいイ、オ`,
but I'm not sure if this is correct.




If you can pronounce バート correctly in the Japanese way, that's it. Simply
elongate バ as it is actually spelled. As long as your pronunciation is clear,
no one will be confused between バート and バト. (Read
[this](https://japanese.stackexchange.com/q/65027/5010) and
[this](https://japanese.stackexchange.com/q/73355/5010) if you have doubts.)
The same for ティオ. By the way, conveying kanji over the phone can be [much
trickier](https://japanese.stackexchange.com/a/9572/5010).

If this fails and you do need to explain, you can say バは伸{の}ばします (" _Ba_ is
elongated").

If this fails and you do have to tell the spelling character by character, the
`－` symbol is called 伸ばし【のばし】棒【ぼう】 or 長音符【ちょうおんぷ】, so you can say
"カタカナでバ、伸{の}ばし棒{ぼう}、ト". For ティオ, yes, "テ、小さいイ、オ" works perfectly.

If everything above fails, there is something like
[this](https://en.wikipedia.org/wiki/Japanese_radiotelephony_alphabet) as a
last resort, but I doubt you would ever need this.




If you can pronounce バート correctly in the Japanese way, that's it. Simply
elongate バ as it is actually spelled. As long as your pronunciation is clear,
no one will be confused between バート and バト. (Read
[this](https://japanese.stackexchange.com/q/65027/5010) and
[this](https://japanese.stackexchange.com/q/73355/5010) if you have doubts.)
The same for ティオ. By the way, conveying kanji over the phone can be [much
trickier](https://japanese.stackexchange.com/a/9572/5010).

If this fails and you do need to explain, you can say バは伸{の}ばします (" _Ba_ is
elongated").

If this fails and you do have to tell the spelling character by character, the
`－` symbol is called 伸ばし【のばし】棒【ぼう】 or 長音符【ちょうおんぷ】, so you can say
"カタカナでバ、伸{の}ばし棒{ぼう}、ト". For ティオ, yes, "テ、小さいイ、オ" works perfectly.

If everything above fails, there is something like
[this](https://en.wikipedia.org/wiki/Japanese_radiotelephony_alphabet) as a
last resort, but I doubt you would ever need this.

