Acronyms are often substituted for commonly used expressions. Here are a few of the more common ones that you might see in the Bentley discussion groups:
AFAIK - As Far As I Know
AKA - Also Known As
ASAP - As Soon As Possible
BTW - By the Way
ETA - Estimated Time of Arrival
FAQ - Frequently Asked Question
FWIW - For What It's Worth
FYI - For Your Information
HTH - Hope This Helps
IMHO - In My Humble Opinion
IOW - In Other Words
NDA - Non-Disclosure Agreement
NRN - No Reply Necessary
OTOH - On the Other Hand
PMFJI - Pardon Me for Jumping In
TIA - Thanks in Advance
WAD - Works as Designed
WRT - With Respect To
You can find definitions of other acronyms at Web sites like http://www.acronymfinder.com/ or http://www.ucc.ie/info/net/acronyms/