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BER: variable-length big-endian binary representation (up to 2 2 1024 bits); PER Unaligned: a fixed number of bits if the integer type has a finite range; a variable number of bits otherwise; PER Aligned: a fixed number of bits if the integer type has a finite range and the size of the range is less than 65536; a variable number of octets ...
In computer programming, Base64 is a group of binary-to-text encoding schemes that transforms binary data into a sequence of printable characters, limited to a set of 64 unique characters. More specifically, the source binary data is taken 6 bits at a time, then this group of 6 bits is mapped to one of 64 unique characters.
A binary-to-text encoding is encoding of data in plain text. More precisely, it is an encoding of binary data in a sequence of printable characters . These encodings are necessary for transmission of data when the communication channel does not allow binary data (such as email or NNTP ) or is not 8-bit clean .
hexBinary and base64Binary: binary data encoded as hexadecimal or Base64; anyURI: a URI; QName: a qualified name; NOTATION: a QName declared as a notation in the schema. Notations are used to embed non-XML data types. [18] This type cannot be used directly - only derived types that enumerate a limited set of QNames may be used.
On the other hand, if the input has many 8-bit characters, then Quoted-Printable becomes both unreadable and extremely inefficient. Base64 is not human-readable, but has a uniform overhead for all data and is the more sensible choice for binary formats or text in a script other than the Latin script.
In order to facilitate a choice between encoding rules, the X.690 standards document provides the following guidance: The distinguished encoding rules is more suitable than the canonical encoding rules if the encoded value is small enough to fit into the available memory and there is a need to rapidly skip over some nested values.
A number of schemes exist to pack 8-bit data into text-only representations which can pass through text mail systems, to be decoded at the destination. Examples of 6-bit character subsets used for packing binary data include Uuencode and Base64. These sets contain no control characters (only printable numbers, letters, some punctuation, and ...
More common today is the Base64 format, which is based on the same concept of alphanumeric-only as opposed to ASCII 32–95. All three formats use 6 bits (64 different characters) to represent their input data. Base64 can also be generated by the uuencode program and is similar in format, except for the actual character translation: