[File] Magic for Stata data files

[Rémi Rampin]

Hi,

Stata is a statistical software tool that was created in 1985. While I
don't personally use it, data files in its native (proprietary) format
are common (.dta files).

Because they are so common, especially in statistical and social
sciences, Stata files and SPSS files can be opened by a lot of modern
software, for example Python's pandas package provides built-in
support for them (read_stata() and read_spss()).

I noticed that the magic database includes an entry for SPSS files but
not Stata files. Stata files for Stata 13 and newer (formats 117, 118,
and 119) always begin with the string "<stata_dta><header>" as per
https://www.stata.com/help.cgi?dta#definition

The format version number always follows, for example:
    <stata_dta><header><release>117</release>
    <stata_dta><header><release>118</release>

Therefore the following line would do the trick:
    0       string  <stata_dta><header>     Stata Data File

(I'm sure the version number could be captured as well but I did not
manage this without a regex)

Unfortunately the previous formats (created by Stata before 13, which
was released 2013) are harder to recognize. Format 115 starts with the
four bytes 0x73010100 or 0x73020100, format 114 with 0x72010100 or
0x72020100, format 113 with 0x71010101 or 0x71020101.

For additional reference, the Library of Congress website has an entry
for the Stata Data File Format 118:
https://www.loc.gov/preservation/digital/formats/fdd/fdd000471.shtml

Example of those files can be found on Zenodo:
https://zenodo.org/search?page=1&size=20&q=&file_type=dta

Best regards
-- 
Rémi Rampin
Research Engineer, New York University