[IUCr Home Page] [CIF Home Page]

Index

Powder dictionary (pdCIF) version 1.0.1

_pd_block_id

Name:
'_pd_block_id'

Definition:

   Used to assign a unique character string to a block.
   Note that this code is not intended to be parsed; the
   concatenation of several strings is used in order to
   generate a string that can reasonably be expected to
   be unique.

   This code is assigned by the originator of the data set and
   is used for references between different CIF blocks.
   The ID will normally be created when the block is first
   created. It is possible to loop more than one ID for a
   block: if changes or additions are made to the
   block later, a new ID may be assigned, but the original name
   should be retained.

   The format for the ID code is:
     <date-time>|<block_name>|<creator_name>|<instr_name>

    <date-time>    is the date and time the CIF was created
                   or modified.

    <block_name>   is an arbitrary name assigned by the
                   originator of the data set. It will
                   usually match the name of the phase
                   and possibly the name of the current CIF
                   data block (i.e. the string xxxx in a
                   data_xxxx identifier). It may be a sample name.

    <creator_name> is the name of the person who measured the
                   diffractogram, or prepared or modified the CIF.

    <instr_name>  is a unique name (as far as possible) for
                   the data-collection instrument, preferably
                   containing the instrument serial number for
                   commercial instruments. It is also possible to
                   use the Internet name or address for the
                   instrument computer as a unique name.

   As blocks are created in a CIF, the original sample identifier
   (i.e. <block_name>) should be retained, but the <creator_name>
   may be changed and the <date-time> will always change.
   The <date-time> will usually match either the
   _pd_meas_datetime_initiated or the _pd_proc_info_datetime
   entry.

   Within each section of the code, the following characters
   may be used:
                 A-Z a-z 0-9 # & * . : , - _ + / ( ) \ [ ]

   The sections are separated with vertical rules '|' which are
   not allowed within the sections. Blank spaces may also
   not be used.  Capitalization may be used within the ID code
   but should not be considered significant - searches for
   data-set ID names should be case-insensitive.

   Date-time entries are in the standard CIF format
   'yyyy-mm-ddThh:mm:ss+zz' Use of seconds and a time zone
   is optional, but use of hours and minutes is strongly
   encouraged as this will help ensure that the ID code is unique.

   An archive site that wishes to make CIFs available via
   the web may substitute the URL for the file containing the
   appropriate block for the final two sections of the ID
   (<creator_name> and <instr_name>). Note that this should
   not be done unless the archive site is prepared to keep the
   file available online indefinitely.

Examples:

1991-15-09T16:54|Si-std|B.Toby|D500#1234-987
1991-15-09T16:54|SEPD7234|B.Toby|SEPD.IPNS.ANL.GOV

May appear in list

Type: char

Category: pd_block