X.690 is an ITU-T standard specifying several ASN.1 encoding formats: Basic Encoding Rules (BER) Canonical Encoding Rules (CER) Distinguished Encoding Rules (DER) The Basic Encoding Rules (BER) were the original rules laid out by the ASN.1 standard for encoding data into a binary format. The rules, collectively referred to as a transfer syntax in ASN.1 parlance, specify the exact octets (8-bit byt