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[ddlm-group] Trailing whitespace in CIF2.0 text fields: statementfrom draft syntax chapter of Vol G

  • To: ddlm-group <ddlm-group@iucr.org>
  • Subject: [ddlm-group] Trailing whitespace in CIF2.0 text fields: statementfrom draft syntax chapter of Vol G
  • From: James H <jamesrhester@gmail.com>
  • Date: Wed, 5 May 2021 11:18:17 +1000

Dear DDLm group, 

In your capacity as technical advisory committee for CIF, please note the following excerpt from the final draft of the new Volume G syntax chapter. I'm bringing this to your attention as it contains a statement about significant trailing whitespace that was not explicit in the CIF2.0 paper, so out of an abundance of caution I thought it best to make sure there were no objections.  If you do have substantial objections, please let the group know.




Additionally, in view of the record-oriented text file formats that are conventional in some environments, and because of some programming languages' record-oriented text input / output interfaces and fixed-length character data types, some CIF 1.1 processors may be unable easily to recognize significant in-line whitespace at the ends of lines of a text field, and some CIF 1.1 writers may pad lines, including lines of text fields, with insignificant whitespace characters. Therefore, trailing whitespace in CIF 1.1 text field lines is considered insignificant. It should be elided where feasible, and if not elided, it should be ignored. Significant trailing whitespace can be marked and protected by use of the line-folding protocol. On the other hand, because CIF 2.0 is a binary byte stream format with explicit line termination sequences, no such considerations apply to multiline data values (text fields and triple-quoted strings) expressed in that syntax, and all trailing whitespace is significant. In view of CIF 1.1 behaviour, however, it is recommended that significant trailing whitespace be avoided in CIF 2.0 text fields. As with CIF 1.1, this can be achieved by applying the line-folding protocol if necessary.

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