PocketPC hacking abbreviations

I finally found these abbreviations on xda-developers!
I'm planning to try flashing some other ROMs to my HTC Kaiser, so I need to understand what the hell all this stuff means.
First I'm going to dump my existing ROM so I can get backto the original state if desired.
After that I'll stick the Hard-SPL on my Kaiser. This apparently lets you play around more safely with ROMs. I.e. there's less chance of ending up with a very expensive brick instead of a phone!

clipped from wiki.xda-developers.com Describe Acronyms here. Adaptation Kit Update ( AKU ) - they usually patch up existing bugs and enable several new features. Each newly released AKU pack retains fixes found in previous versions of AKU ( CID lock ) - aka VENDOR LOCK put on your device by the manufacturer to prevent installation of a ROM not released by them Radio Interface Layer ( RIL ) ROM Upgrade Utility ( RUU ) - Its the s/w used on ur PC to do ROM upgrade for your PPC ( IPL/SPL ) - Its the bootloader for PPC. IPL is the Initial Program Loader. It boots up SPL - Secondary Program Loader. SPL in turn loads the actual OS. World Wide English Edition ( WWE Edition ) XIP - Execute-in-Place More at FAQ section