From the supply depôts the supplies and stores pass on to the _Regulating Station_ ("gare régulatrice"). This is located at such point on each line of communication as, while allowing of a final regulation of supplies going to the front, does not--owing to its nearness to the fighting line--permit of any guarantee of a fixed train service beyond that point. The locality of the regulating station is changed from day to day, or from time to time, according to developments in the military situation. The regulating station is in charge of a _Regulating Commission_ ("Commission régulatrice"), constituted on the same basis as a Sub-Line Commission. Receiving orders or instructions as to the nature and quantities of the supplies and stores required by the troops at the front, and drawing these from the supply depôts, the Commission must always have on hand a sufficiency to meet requirements. It is, also, left to the Commission to arrange for the further despatch of the supplies from the regulating station by means of such trains as, in the circumstances of the moment, may be found practicable. As a matter of daily routine, and without further instructions, the supply depôts send one train of provisions each day to the regulating station, and the latter sends on one train daily to the front, always, however, keeping a further day's supply on hand, at or near the regulating station, to meet further possible requirements. Additional trains, whether from the supply depôts or from the regulating station (where rolling stock is kept available) are made up as needed. Supplementing these arrangements, the Regulating Commission may, at the request of the Director of Road Services, further keep permanently within its zone of action a certain number of wagons of provisions in readiness to meet contingencies, the wagons so utilised as _Stores on wheels_ being known as "en-cas mobiles." Should the Directeur de l'Arrière so desire, railway wagons with ammunition can, in the same way, be kept loaded at any station within the Zone of the Armies, or, by arrangement with the Minister of War, in the Zone of the Interior. It is, however, stipulated that the number of these wagons should be reduced to a minimum, in order to avoid congestion either of the stations or of the railway lines. Beyond the regulating station comes _Railhead_, which constitutes the furthest limit of possible rail-transport for the time being, and the final point of connection between rail and road services, the latter being left with the responsibility of continuing the line of communication thence to the armies on the field of battle.