NeTEx is a CEN standard, the formal documents describing the standard are available as Technical Specifications (TS) from your national standardisation body. A fee in the national currency is charged for such documents by each standardisation body. However the actual formats and designs described by the TS may be used without charge, and without necessarily purchasing the CEN NeTEx publications. You may use the schema and models for free under a GPL license as described on NeTEx web site (http://netex-cen.eu/?page_id=20). This ensures that the IPR is in the public domain and may be safely considered as a long term strategic investment.
The NeTEx schema itself is a W3C XML schema, so XML technical skills are typically required to build applications to create or process data in NeTEx format. General XML skills can be used to process XML documents containing data in NeTEx format, for example, to run validators or to amend content.
At a design level, NeTEx uses a “Model Driven” approach, that is, the fundamental design is described as a high level conceptual model that tries to represent the problem domain as entities and relationships that have been identified by a set of use cases, many taken from existing systems covering the desired business scope. To understand the high level model underlying the XML schema (which is valuable for building applications) requires data modelling skills and an understanding of the UML notation. Public Transport domain knowledge will of course help (additional information available at http://transmodel-cen.eu/).
General purpose XML tools can be used to work with the NeTEx XML schema and XML documents that conform to it, for example either the proprietary XML SPY (http://www.altova.com/xmlspy.html), or Oxygen (http://www.oxygenxml.com/) or see free tools at http://www.garshol.priv.no/download/xmltools/. A wide variety of mainstream XML tools are available to validate XML and to create bindings to specific programming languages (.NET, Java, PHP, C++).
To look at the design models, an interactive UML viewer such as Enterprise Architect (http://www.sparxsystems.com/) is extremely helpful, although a set of static web pages is also available.
To import or export transport data in NeTEx format, a number of suppliers are developing support for NeTEx for their existing products. New open source NeTEx products are also being developed such as CHOUETTE (http://www.chouette.mobi/en/). Sample mappings to a variety of national formats (VDV, BISON, etc) as well as GTFS have been developed and are included in the NeTEx standard. Further information on NeTEx implementations are available at http://netex-cen.eu/?page_id=65.
CEN working groups provide a consensual process to evolve standards and have formal procedures and timeframes managed through the standards bodies of the European nations. New feature proposals can be submitted to the NeTEx working group by sending an email at info<at>netex-cen.eu and will be considered along with other suggestions for a future enhancement to the standard. Under the CEN process a New Work Item request is created to manage the enhancements to a specification, with a versioning process to identify sets of changes.
Adding new features specific to country, supplier or any smaller area can be done using NeTEx extension mechanisms (Key Value extensions/ Extension Tag). These can also be used to develop new candidate features ahead of formal incorporation. See also ‘Can I add my own codes to NeTEx’?
Although NeTEx is a large standard, a NeTEx service needs only to implement the specific elements relevant to its business objectives – extraneous elements present in the model can be ignored. Parties using NeTEx for a particular purpose will typically define a “profile” to identify the subset of elements that must be present, as well as the code sets to be used to identify them. A machine readable form of this profile may be created using the NeTEx TYPE OF FRAME element, specifying which elements must be present; this can be used to enable automatic validators for local profiles.
Following are some profile examples:
Any issue on NeTEx can be communicated to the working group sending an email at info <at> netex-cen.eu. NeTEx schemas are in GITHUB and corrected versions, identified by an interim version number, can be created if necessary.
Some basic support for NeTEx development can be get sending an email at info <at> netex-cen.eu.