Petter Reinholdtsen

MIME type "text/vnd.sosi" for SOSI map data
20th May 2019

As part of my involvement in the work to standardise a REST based API for Noark 5, the Norwegian archiving standard, I spent some time the last few months to try to register a MIME type and PRONOM code for the SOSI file format. The background is that there is a set of formats approved for long term storage and archiving in Norway, and among these formats, SOSI is the only format missing a MIME type and PRONOM code.

What is SOSI, you might ask? To quote Wikipedia: SOSI is short for Samordnet Opplegg for Stedfestet Informasjon (literally "Coordinated Approach for Spatial Information", but more commonly expanded in English to Systematic Organization of Spatial Information). It is a text based file format for geo-spatial vector information used in Norway. Information about the SOSI format can be found in English from Wikipedia. The specification is available in Norwegian from the Norwegian mapping authority. The SOSI standard, which originated in the beginning of nineteen eighties, was the inspiration and formed the basis for the XML based Geography Markup Language.

I have so far written a pattern matching rule for the file(1) unix tool to recognize SOSI files, submitted a request to the PRONOM project to have a PRONOM ID assigned to the format (reference TNA1555078202S60), and today send a request to IANA to register the "text/vnd.sosi" MIME type for this format (referanse IANA #1143144). If all goes well, in a few months, anyone implementing the Noark 5 Tjenestegrensesnitt API spesification should be able to use an official MIME type and PRONOM code for SOSI files. In addition, anyone using SOSI files on Linux should be able to automatically recognise the format and web sites handing out SOSI files can begin providing a more specific MIME type. So far, SOSI files has been handed out from web sites using the "application/octet-stream" MIME type, which is just a nice way of stating "I do not know". Soon, we will know. :)

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Tags: english, kart, noark5, standard.

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