The current 9ML specification is version 1.0. There is also a development branch, which contains revisions to the specification that have been approved by the NineML committee but have not been released.
There is a corresponding XML schema although the schema only validates the model hierarchy and basic types, i.e. not all the requirements described in the specification.
For full validation of 9ML models, please use the officially supported NineML Python Library. Software written in Python, or with a Python interface, can also take advantage of its convenient API in order to add support for 9ML to your tool.
For 9ML examples, please see the NineML Catalog.