[hyghjiyhu]

I think getting hung up on words (in this case index) in mathematics is a trap. They are often stretched to their breaking point and you just kind of go with the flow.

> When I use a word,’ Humpty Dumpty said in rather a scornful tone, ‘it means just what I choose it to mean — neither more nor less.’

> ’The question is,’ said Alice, ‘whether you can make words mean so many different things.’

> ’The question is,’ said Humpty Dumpty, ‘which is to be master — that’s all.

In mathematics it is the author's privilege.