Hi, Alvin. I have a few questions about this.

1. In standard use of katakana, that horizontal line after the pa usually indicates that the vowel is spoken for a slightly longer time, almost like an additional syllable. So it is something like a - pa - a - to, with that pa and a merging together, not really separate. This is curious for me because we say "apartment," not "apa-a-rtment." I have always wondered why in this word, as well as the one used to indicate a "department store" - depaato - there is that long line. Apartment - not apaartment. Department store - not depaartment store. Why do they elongate that a? It makes no sense to me.

2. I question why you place the line over the a in your romaji apāto. Usually in English, a long line over a vowel indicates that it is pronounced as a long vowel: ā would be pronounced as in "cable." Doesn't it make more sense to write it as apaato (ah-pah-ah-to), if you are pronouncing it with the elongated a sound?

I'l confess I often have problems with katakana because of how flawed it is at trying to represent foreign words. In our Nihonmachi, one street that runs through it is Webster Street, which is represented in katakana as We-bu-su-tah - nothing like Webster.

Yours in better understanding....