Networkx read ordnance survey - ITN Integrated Transport Network?/Reading GML file

I met some problems.

I want to import ordnance survey - ITN Integrated Transport Network into networkx to do some network analysis.

Since the ITN is in a GML 2.1.2 format, I tried to use

nx.read_gml

However it warned me that

ParseException: Expected "graph" (at char 0), (line:1, col:1)

Then, I took sometime to look at the content of my file and find out that it is not like a gml file used in someone else's example. It does not have graph or square bracket or nodes. Am I understand this format right?

https://www.dropbox.com/s/3ppgs3t9t6odkpj/os-mastermap-itn-layer-sample-data.gml?dl=0

I have attached it above, the first lines indside it are:

<?xml version='1.0' encoding='UTF-8'?>
<osgb:FeatureCollection
xmlns:osgb='http://www.ordnancesurvey.co.uk/xml/namespaces/osgb'
xmlns:gml='http://www.opengis.net/gml'
xmlns:xlink='http://www.w3.org/1999/xlink'
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xsi:schemaLocation='http://www.ordnancesurvey.co.uk/xml/namespaces/osgb http://www.ordnancesurvey.co.uk/xml/schema/v7/OSDNFFeatures.xsd'
fid='GDS-1614256-8519'>

I get a little bit confused that why the gml format seems different? Anyone has tried to use networkx or python analyse ITN data?

Solution

It looks like the GML you are citing is the Geography Markup Language https://en.wikipedia.org/wiki/Geography_Markup_Language and the GML referred to in NetworkX is the Graph Modeling Language https://en.wikipedia.org/wiki/Graph_Modelling_Language.