The Deutsche Bahn AG in Germany reserves classes 088, 188 and 288 for all historical motive power (locomotives, multiple-units, railcars and railbuses) that are no longer part of their active, commercial fleet, but are still in their inventory. These classes are however, generally, 'virtual' because whilst they are used in the computerised database for management purposes, the running numbers are usually only recorded in the cab of the actual vehicle. Externally the original vehicle numbers are displayed.
These group classes have the following definitions:
References
DBAG Class 088 Wikipedia(Text) CC BY-SA