This datatype allows characters that are not allowed in XML markup to be represented. These primarily include are control characters. While this might be a reasonable technique for encoding binary data, as an alternative to XML Schema’s Bin16 and Bin64 encodings, an examination of the elements which are defined using this datatype shows many if not all are simple strings, such as author name. As a consequence, this datatype is highly undesirable and bad practise. In the particular case where a data field is basically textual however it may be generated by a system that does not follow XML conventions, then this data type may be used.

In almost all cases in s3.18.96 and associated schema components, change the type to reference xsd:String instead of ST_Xstring. The normal XML restrictions will then apply. This must be done for all uses in names, titles, ids, numbers, formats, captions, etc. (Where a data field is basically textual however it may be generated by a system that does not follow XML conventions, then this data type may be used.)

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Proposed Disposition of DIS 29500 Comment AU-0023 (Modified: 2007-11-24) We agree that the use of this data type should be limited as much as possible. The reason it exists is because there are characters that are valid in SpreadsheetML content, but are not valid according to the XML string data type (for instance, the Unicode character 8 [BACKSPACE] is invalid in an XML 1.0 document). (Such characters can be entered via the CHAR function.) We have reviewed the usage of the ST_Xstring type and confirmed that its usage is limited to only those places where the content cannot be controlled by the file format (i.e., user strings, data from external data sources, etc.). No change will be made.