An XML schema (XSD) is a description of a type of XML document, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntactical constraints imposed by XML itself.

The official TAF TSI XSD schema is mantained and developed by the Change Control Management (CCM) process managed by the European Union Agency for Railways (ERA). Nevertheless, the rail sector working groups have added their changes which are not expected to be included in Regulatory framework, but implemented and used in bilateral business agreements.

The following versions of the XSD Schemas:

• The official XSD Schema approved by TAF/TAP TSI Change Control Board (CCB) and published at the ERA website here.
• The Sector XSD Schema is the “candidate” schema where the sector messages are added in order to use the existing global elements of TAF data catalogue. The sector messages are outside of the official TAF data catalogue and they are owned, used and maintained by the rail sector. All versions of the TAF/TAP TSI sector schema starting from version 2.1.2 are available here.