This binary element is intended to store "arbitrary user-defined data", but give no details about the actions, that actually initiate the usage of this binary element. This seem to introduce a large "unknown" container into which any binary information can be stored. Without any detailed definition it is impossible to implement any kind of interoperability to such a "construct"

Suggest that the custom XML mapping part shall only be used when no other mapping parts in ISO/IEC 29500 OOXML apply.

Page 68
line 22 Part 1
Section 12.3.5

Ed

Proposed Disposition of DIS 29500 Comment DK-0102 (Modified: 2008-01-11) Agreed; the following changes will be made to Part 1, §12.3.5, page 68, lines 24­32: 12.3.5 Custom Property Part Content Type: Any content, support for which is application-defined. [Note: Some examples of formats which might be supported include: application/vnd.openxmlformats-officedocument.spreadsheetml.customProperty application/xml end note] Root Namespace: Not applicable Source Relationship: http://schemas.openxmlformats.org/officeDocument/2006/relationships/customProperty This binary part supports the storage of arbitrary custom user-defined data. [Note: It is recommended that a Custom Property Part contain XML content for improved interoperability; however, there is no requirement on the format of the content contained in a Custom Property Part. end note] A n instance of this part type A package shall contain correspond to at most one Custom Property part, and that part shall be the target of an implicit relationship from the Workbook Worksheet (§12.3.24) (§12.3.23) part. A package can contain more than one Custom Property Part. [Example: The following Workbook Worksheet part-relationship item contains a relationship to the Custom Property part, which is stored in the ZIP item CustomProperty. bin xml : <Relationships xmlns="..."> <Relationship Id="rId7" Type="http://.../customProperty" Target="CustomProperty. bin xml "/> </Relationships> where the contents of CustomProperty.xml could contain the following XML <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <CustomApplicationData xmlns="..."> <CustomProperty name="PropertyName" value="PropertyValue" /> </CustomApplicationData> end example] Similar Comments: CA-0009 , CL-0042 , CL-0047 , CL-0052 , DE-0007 , FR-0015 , GB-0042 , JP-0037 , PT-0010 , US-0034