Name
xs:base64binary
Facets
xs:enumeration,
xs:length, xs:maxLength, xs:minLength, xs:pattern, xs:whiteSpace |
The xs:base64binary type
is designed to contain information represented using the Base64
algorithm described in RFC 2045 (http://ietf.org/rfc/2045.txt). Base64 encoding
allows applications to encode binary data as ASCII text and
retrieve it again after transmission. The only characters allowed
in Base64-encoded data are the letters A–Z
and a–z, the numbers 0–9,
and the symbols plus (+) and
slash (/). The encoding uses 4
bytes for every three of these characters. The data is represented
in 76-character lines (because of its origins as part of the MIME
mail rules) separated by line feeds. The equals sign (=) is used to pad lines if
necessary.
Tip
The Base64 algorithm has been separated from RFC 2045 into a separate specification, RFC 3548 (http://ietf.org/rfc/3548.txt). While that’s a more convenient place to locate details of the algorithm, the XML Schema specification still normatively references RFC 2045.
While Base64 encoding is hardly an efficient means of
transporting information, it is somewhat more efficient than the
other type XML Schema provides for this task, xs:hexBinary.
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