The Yellow Book is no longer being maintained. Yellow Book Issue 4 has the status of a withdrawn document and does not represent up-to-date guidance for the GB mainline railway. Yellow Book issue 4 continues to be available for organisations to use if they wish, but all organisations should note that the guidance contained within it no longer aligns with the current regulatory regime that applies to the GB mainline railway system.

Work is currently underway to provide updated guidance.

The following companies were endorsed to deliver examined and certificated 'Yellow Book 4' training courses:

Lloyds Register Rail

Altran Praxis Limited

ESR Technology