The Signalling Diagrams Register is been developed to index a large collection of Signalling Diagrams,
Signalbox Diagrams, Locking Charts, Locking Tables, and other related diagrams, and to integrate the indexing into RailRef.
The register currently contains 4,811
records,
and the whereabouts of 22
individual copies of those publications.
Access to the register is restricted as development progresses, and is not ewxpected to be useable until mid-2021.