A Brief Introduction to Abstract Syntax Notation One (ASN.1) and Basic Encoding Rules (BER)

The following is a list of commonly used standards that are written in ASN.1:

• X.400 (Electronic Messaging)
• X.500 (Directory Services)
• X.200 (Network communications)
• Request for Comments (RFCs) 2251-2256 (Lightweight Directory Access Protocol, or LDAP)
• Too many other RFCs to mention

http://support.microsoft.com/kb/252648