Who's Katie?

I've read stories about Manson, and this is the only one where anyone named Katie was mentioned. I had never heard of her before. At the end the Manson girls mentioned were Susan Atkins, Leslie Van Houten, Patricia Krenwinkle, and Linda Kasabian. Was Katie a nickname for Patricia. I also never remember hearing about Clem, but it seems Clem only played part in an attempted murder that was thwarted on purpose by Kasabian, so the other stories didn't find him important. Also I thought Linda always drove or did they just always use her car? Anybody have answers? Thanks.

Evan