[File] Magdir for Data Interchange Format; *.dif

[Christos Zoulas]

Committed thanks!

christos

> On Apr 5, 2020, at 6:58 PM, Jörg Jenderek <joerg.jen.der.ek at gmx.net> wrote:
> 
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> Hello,
> 
> some days ago i used SoftMaker Office. The spreadsheet module can
> read/read documents with filename extension dif.
> When running file command version 5.38 on such documents these
> examples are described generic as text.
> 
> For comparison reason i also run other file identifying tools.
> TrID ( See https://mark0.net/soft-trid-e.html ) identifies such
> documents as "Data Interchange Format"
> DROID ( See https://digital-preservation.github.io/droid/ )
> describes some documents as "VisiCalc Database" by x-fmt/368 or
> x-fmt/41.
> 
> Information about that file format can be found on file formats
> archive team website and on Wikipedia. This is expressed by comment
> lines like:
> # URL: http://en.wikipedia.org/wiki/Data_Interchange_Format
> # http://fileformats.archiveteam.org/wiki/Data_Interchange_Format
> According to documentation characteristic at the beginning of
> document is upcased text identifier TABLE. That is used as
> first test line:
> 0	string		TABLE
> Unfortunately this is still not unique enough. To skip text starting
> with phrase TABLE look for numeric version number on 2nd line (CRNL
> or NL terminated) by additional test line:
>> 6	search/2	0,
> At this point identification is still not unique. To skip DROID
> x-fmt-41-signature-id-380.dif look at the beginning for upcased text
> identifier TUPLES by third test line
>>> 27	search/128	TUPLES		Data Interchange Format
> 
> Data Interchange Format (.dif) is a text file format used to
> import/export single spreadsheets between spreadsheet programs
> (OpenOffice.org Calc, Excel, Gnumeric, StarCalc, Lotus 1-2-3,
> FileMaker, dBase, Framework, Multiplan, PlanMaker etc). Sometimes
> a generator comment like EXCEL is found on third line enclosed in
> double quotes (="=0x22). Two double quotations with no space between
> if it is not used. So show this information if available by lines
>>>> 10	search/3	"
>>>>> &0	ubyte		!0x22		\b, generator or table name
>>>>>> &-2		string	x	%s
> 
> According to documentation extension dif is used. This is expressed
> by line
> !:ext	dif
> 
> Because DIF examples are just pure test files generic mime type
> "text/plain" could be used. Well suited seems to be
> application/x-dif-spreadsheet but this explanation for dif found on
> pcmatic.com web site was not so precisely. I find this type some
> times for Gnumeric. The type application/vnd.ms-excel is found on
> systems with registered name "Microsoft Office Excel Data Interchange
> Format".
> LibreOffice and OpenOffice sometimes seems to use
> application/x-dif-document.
> Most often seems to be used application/x-dif. That type is also
> mentioned on Wikipedia list of file formats. So i choose this type.
> That is expressed by line:
> !:mime	application/x-dif
> 
> After applying the above mentioned modifications by appended DIF.txt
> then all inspected Data Interchange Format examples are now described
> correctly and i get an output like:
> 
> lsusb-wiko.dif:                ASCII text
> PGP262I.DIF:                   ASCII text, with CRLF line terminators
> TABLE.txt:                     ASCII text, with CRLF line terminators
> x-fmt-41-signature-id-380.dif: ISO-8859 text
> visicalc.dif:                  Data Interchange Format
> LibreOffice-dif.dif:           Data Interchange Format,
>                               generator or table name "MyTable1"
> planmaker-dif.dif:             Data Interchange Format,
>                               generator or table name "pmw"
> excel-dif.dif:                 Data Interchange Format,
>                               generator or table name "EXCEL"
> 
> Because file format is pure text magic lines maybe belong to
> Magdir/wordprocessors. Because file format is a spreadsheet the lines
> maybe belong to Magdir/database.
> The remaining DIFs are real pure text like PGP262I.DIF or output of
> diff command.
> 
> I hope my lines for Magdir can be applied in future version of file
> utility.
> 
> With best wishes
> Jörg Jenderek
> - --
> Jörg Jenderek
> 
> 
> 
> 
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> <DIF.txt><DIF_txt_sig.DEFANGED-43>--
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