RFC 1488 X.500 Syntax Encoding July 1993 2. Standard Attribute Syntax Encodings For the purposes of defining the encoding rules for the standard attribute syntaxes, the following auxiliary BNF definitions will be used: ::= 'a' | 'b' | 'c' | 'd' | 'e' | 'f' | 'g' | 'h' | 'i' | 'j' | 'k' | 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' | 's' | 't' | 'u' | 'v' | 'w' | 'x' | 'y' | 'z' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G' | 'H' | 'I' | 'J' | 'K' | 'L' | 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U' | 'V' | 'W' | 'X' | 'Y' | 'Z' ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ::= | 'a' | 'b' | 'c' | 'd' | 'e' | 'f' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' ::= | | '-'
::= | | ''' | '(' | ')' | '+' | ',' | '-' | '.' | '/' | ':' | '?' | ' ' ::= The ASCII newline character with hexadecimal value 0x0A ::= | ::= | ::= | ::= | ::=|
::= ' ' | ' ' 2.1. Undefined Values of type Undefined are encoded as if they were values of type Octet String. 2.2. Case Ignore String A string of type caseIgnoreStringSyntax is encoded as the string value itself. Howes, Kille, Yeong & Robbins