ISO 19136-2, “Geographic information – Geography Markup Language (GML) – Part 2: Extended schemas and encoding rules,” has just been released. This new standard extends the work started back in 2007 with the release of ISO 19136, “Geographic information — Geography Markup Language (GML).” A future ISO 19136-1 will eventually replace the ISO 19136.
It’s amazing to me how many mobile applications make use of geographic data. But of course, with those of us with inquiring minds, the question of how that data is transported is always of interest. And since I’ve been following mark-up languages since the earliest days of SGML, I’m always struck how the original concept has been flexible enough to go through so many iterations. Where would we be without HTML and all the rest?
So here we are with GML, an XML grammar written in an XML schema for the transport and storage of geographic information. This new ISO 19136-2 extends the original concepts of the ISO 19136 by providing you with specific XML encodings. It supports two different methodologies for such applications. First you can use the schema presented in this standard. Second, you can construct schemas according to ISO 19109 and map them to GML application schemas of ISO 19136-2.
What exactly will you find in the ISO 19136-2? The standard defines the XML Schema syntax, mechanisms and conventions for GML. It contains a scope clause that defines the requirements of such a schema. Clause 2 covers conformance. And Clause 3 is for the usual referenced standards. Next is your section on terms, symbols, and abbreviations. Clause 5 covers conventions such as MIME types, XML namespaces, and so on.
Clauses 6 through 12 specify conformance classes. These include additional base types, compact encodings of GML geometries, triangulated irregular networks, linear referencing, ReferenceableGrid, code lists, directories and definitions, and the encoding rule. Various types of geographical information is defined and turned into code in these clauses. Here’s where you’ll find examples of tag after tag after tag! And you’ll find tables that specify the various requirements class as well.
The standard is completed with Annex A for linear referencing method examples. And then finally there’s a 13-item Bibliography with resources including additional ISO standards of interest, a W3C reccomendation, and a W3C Team submission.
Now to get your copy of this 88-page standard. Since it’s a copyright document, you’ll want to purchase your copy of ISO 19136-2 from an authorized dealer like Document Center Inc. You can easily order either a paper format or pdf download copy of the standard at our webstore, www.document-center.com. Here’s a link directly to the order page for ISO 19136-2.
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