Index

Image dictionary (imgCIF) version 1.3.2

_array_data.data

Definition:

   The value of _array_data.data contains the array data
   encapsulated in a STAR string.

   The representation used is a variant on the
   Multipurpose Internet Mail Extensions (MIME) specified
   in RFC 2045-2049 by N. Freed et al.  The boundary
   delimiter used in writing an imgCIF or CBF is
   "--CIF-BINARY-FORMAT-SECTION--" (including the
   required initial "--").

   The Content-Type may be any of the discrete types permitted
   in RFC 2045; 'application/octet-stream' is recommended.
   If an octet stream was compressed, the compression should
   be specified by the parameter 'conversions="x-CBF_PACKED"'
   or the parameter 'conversions="x-CBF_CANONICAL"'.

   The Content-Transfer-Encoding may be 'BASE64',
   'Quoted-Printable', 'X-BASE8', 'X-BASE10' or
   'X-BASE16' for an imgCIF or 'BINARY' for a CBF.  The
   octal, decimal and hexadecimal transfer encodings are
   for convenience in debugging and are not recommended
   for archiving and data interchange.

   In an imgCIF file, the encoded binary data begin after
   the empty line terminating the header.  In a CBF, the
   raw binary data begin after an empty line terminating
   the header and after the sequence:

   Octet   Hex   Decimal  Purpose
     0     0C       12    (Ctrl-L) page break
     1     1A       26    (Ctrl-Z) stop listings in MS-DOS
     2     04       04    (Ctrl-D) stop listings in UNIX
     3     D5      213    binary section begins

   None of these octets are included in the calculation of
   the message size or in the calculation of the
   message digest.

   The X-Binary-Size header specifies the size of the
   equivalent binary data in octets.  If compression was
   used, this size is the size after compression, including
   any book-keeping fields.  An adjustment is made for
   the deprecated binary formats in which eight bytes of binary
   header are used for the compression type.  In this case,
   the eight bytes used for the compression type are subtracted
   from the size, so that the same size will be reported
   if the compression type is supplied in the MIME header.
   Use of the MIME header is the recommended way to
   supply the compression type.  In general, no portion of
   the  binary header is included in the calculation of the size.

   The X-Binary-Element-Type header specifies the type of
   binary data in the octets, using the same descriptive
   phrases as in _array_structure.encoding_type.  The default
   value is 'unsigned 32-bit integer'.

   An MD5 message digest may, optionally, be used. The 'RSA Data
   Security, Inc. MD5 Message-Digest Algorithm' should be used.
   No portion of the header is included in the calculation of the
   message digest.

   If the Transfer Encoding is 'X-BASE8', 'X-BASE10' or
   'X-BASE16', the data are presented as octal, decimal or
   hexadecimal data organized into lines or words.  Each word
   is created by composing octets of data in fixed groups of
   2, 3, 4, 6 or 8 octets, either in the order ...4321 ('big-
   endian') or 1234... ('little-endian').  If there are fewer
   than the specified number of octets to fill the last word,
   then the missing octets are presented as '==' for each
   missing octet.  Exactly two equal signs are used for each
   missing octet even for octal and decimal encoding.
   The format of lines is:

   rnd xxxxxx xxxxxx xxxxxx

   where r is 'H', 'O' or 'D' for hexadecimal, octal or
   decimal, n is the number of octets per word and d is '<'
   or '>' for the '...4321' and '1234...' octet orderings,
   respectively.  The '==' padding for the last word should
   be on the appropriate side to correspond to the missing
   octets, e.g.

   H4< FFFFFFFF FFFFFFFF 07FFFFFF ====0000

   or

   H3> FF0700 00====

   For these hexadecimal, octal and decimal formats only, 
   comments beginning with '#' are permitted to improve 
   readability.

   BASE64 encoding follows MIME conventions.  Octets are
   in groups of three: c1, c2, c3.  The resulting 24 bits
   are broken into four six-bit quantities, starting with
   the high-order six bits (c1 >> 2) of the first octet, then
   the low-order two bits of the first octet followed by the
   high-order four bits of the second octet [(c1 & 3)<<4 | (c2>>4)],
   then the bottom four bits of the second octet followed by the
   high-order two bits of the last octet [(c2 & 15)<<2 | (c3>>6)],
   then the bottom six bits of the last octet (c3 & 63).  Each
   of these four quantities is translated into an ASCII character
   using the mapping:

             1         2         3         4         5         6
   0123456789012345678901234567890123456789012345678901234567890123
   |         |         |         |         |         |         |
   ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/

   with short groups of octets padded on the right with one '='
   if c3 is missing, and with '==' if both c2 and c3 are missing.

   QUOTED-PRINTABLE encoding also follows MIME conventions, copying
   octets without translation if their ASCII values are 32...38,
   42, 48...57, 59, 60, 62, 64...126 and the octet is not a ';'
   in column 1.  All other characters are translated to =nn, where
   nn is the hexadecimal encoding of the octet.  All lines are
   'wrapped' with a terminating '=' (i.e. the MIME conventions
   for an implicit line terminator are never used).

Type: binary

Mandatory item: yes

Category: array_data