WHY do PHP reindex arrays and add integer indexes?

OK, SOMEONE please explain to me me WHY, when passing serialized data from the client to the server, does PHP reindex it all and add integer indexes to my array? Leave it alone, God Dammit!

HOW do I use PHP arrays in a 'normal' way (have them NOT act as associative arrays or ordered maps)?

I want a bleedin' list of items, and NOT having them prefixed with indexes – they're an index by themselves, dammit!

Needed to get this out, as I've spent the WHOLE BLOODY day fucking around with this ...