Proposed response for FPDAM Part 1 CZ-0015

[Shawn Villaron]

Good afternoon,

Here is a proposed first draft response for CZ-0015 regarding the proposal to add new media types and file extensions into the Strict Conformance Class.

WG4 Response

Rejected.

File extensions should not be specified in the ISO/IEC 29500 standard.  The standard covers the content and structure of the files; the file extension is orthogonal to both of these concepts, and hence out of scope.

Furthermore, there are a variety of problems with adding a predefined set of file extensions to the standard.  For example,


1.       file extensions are not a cross-platform technology for identifying the type of content and structure found in a file;

2.       there is no harm for multiple file extensions to use the same content and structure;

3.       forcing implementers to use a predefined set of file extensions quashes innovation and unnecessarily limits the utility of the ISO/IEC 29500 standard.

It is also worthwhile to note that implementations should rely on the content and structure of the files for validation.  File extensions should not be used for validation as file extensions can be easily spoofed and unaligned with the content and structure of the data found within the file.

Historically there are countless examples of innovations associated with using multiple file extensions for files using the same content and structure. Microsoft Office PowerPoint, for example, uses the same content and structure for their .PPT, .PPS and .POT files; the extensions are used to signify to the application how to use the data: .PPT files are for editing and should be opened in the editor; .PPS files are for distribution and should be opened in slide show and, when slide show completes, the application should terminate; and .POT files are to be used as a foundation for new documents.

Additionally there are countless examples of the same file extension being used for different file format version.  Microsoft Office Word, for example, used the same .DOC extension for well over a decade, all the while making changes to the format ( some small and some large ).

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