"index" is very meaningful, it tells me I'm indexing and not counting, otherwise I'd use "count". Confusion between those two often causes off by one errors, so yes it does actually matter and is actually meaningful. You might like "i" or "n" to convey the same meaning, but as I said, I want words not abbreviations.

Of course, it should be `aStreamPosition` rather than `index` - still not `i` ;)