You want to know the rules for using abbreviations and acronyms in type and member names.
Follow these guidelines to determine how you should use abbreviations and acronyms:
1. Avoid abbreviations in type and member names.
2. Only use acronyms if they are well known by developers (e.g. UIThread).
3. Two-character acronyms should use an all-uppercase style.
4. Use PascalCase for acronyms with three or more characters.
These conventions come from Microsoft, but you may notice that some classes in the .NET Framework do not follow them. For example, ASCIIEncoding and CLSCompliant.