SUBSET-114 — KMC-ETCS Entity Off-line KM FIS

Scope

The interface specification between a Key Management Centre and the ETCS entities it serves (on-boards and trackside): message formats, procedures and media for the off-line distribution and management of EuroRadio keys defined functionally in SUBSET-038.

Where SUBSET-038 defines the key-management processes, SUBSET-114 nails down the interface a Key Management Centre uses towards the ETCS entities themselves: the structures and semantics of key-installation, update and deletion transactions, their acknowledgement handling, and the interoperable formats that let an on-board from one supplier receive keys governed by another operator's KMC. Standardising this boundary is what keeps multi-vendor, multi-country ETCS fleets manageable — without it every KMC-to-vehicle relationship would be a bespoke integration. Mandatory at v4.0.0 under Annex A of the 2023 CCS TSI; used by KMC operators, on-board and RBC suppliers, and the fleet engineers who run key campaigns across borders.