For what are these katakana strings in a reclist? (7-mora)

[UTAU~Ayume]

Well i've seen katakanas in a 7-mora hiragana reclist. I honestly don't know what are these for...

Can someone explain this to me? O3O

and if this is the wrong section, gomen ne ... i didn't know where to start that thing D:'

 

[tady159]

Those are said to be extras, to help a little bit with foreign words adapted to Japanese pronunciation. They are in katakana because they represent syllables that are not used in native words.

 

[KitWistful]

Those are said to be extras, to help a little bit with foreign words adapted to Japanese pronunciation. They are in katakana because they represent syllables that are not used in native words.

Second'd. r->l and b->v are the ones I'm guessing that you're looking at.