xs:base64Binary
The xs:base64Binary
type represents an arbitrary sequence of bytes that
has been encoded in ASCII characters using the Base-64 algorithm
defined in RFC 2045, Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies. The letters A-Z and a-z, the digits 0-9, and
the punctuation marks + and / are used to encode data according to
an algorithm that maps four of these characters to three arbitrary
bytes. The equals sign is used to pad data at the end if
necessary.
The constraining facets that apply to xs:base64Binary are length, minLength, maxLength, pattern, enumeration, and whiteSpace. Unlike string types, the
values specified by the length,
minLength, and maxLength facets refer to the number of
bytes in the decoded data, not to the number of characters in the
encoded data.