The endianess (or byte-order) defines the way values are stored in memory.

Lets take an example value of 0x12345678 (hex).

On big-endian systems (MIPS, PPC, IP network packets, etc.) it's stored with the most significant byte first:: 0x12345678

On little-endian systems (x86) it's stored as with the least significant byte first, e.g. as: 0x78563412

You're making this up, right? (And I know you're not, you should just have a link in here linking to how this relates to LSL.
See Preview. I'll put links in here once 1.5 is released and we have pages for the functions it applies to. -Ez

Detailed explanation