A straight lift from the MoD, for a bit of information
The Logistics Support and Sustainability Cycle can broadly be divided into two parts; logistic support (getting the forces ready for the fight) and logistic sustainability (to keep the fight going). This also reflects the funded and unfunded split of the logistic requirement. But there is some overlap as elements of sustainability that cannot be procured within the warning times must necessarily be funded.
Logistic support can be further sub-divided by the ‘readiness lines’. The Force Elements at Readiness (Rx) is where our forces are normally held in peace time against the readiness profile required by Defence (encompasses all our military capabilities). From Rx to Ro, Force Elements required for operations are ‘force generated’ to the point where they are ready to deploy for a given operation. Force Elements at Readiness (Rx) and Force Elements undergoing force generation (Rx to Ro)) are given ‘Logistic Support’ under the terms of Service Delivery Agreements between the Centre, Front Line Commands and the DLO and detailed in CSAs.
Logistic sustainability or operation specific ‘sustainment’ is required to ensure a force can maintain the necessary combat capability to achieve its objectives. From the diagram (clockwise beyond Ro) it can be seen that this phase encompasses the deployment, intheatre training and conduct of operations, through to recovery or redeployment of the force. It also includes recuperation of the returning Force Elements to ensure that future operations can be conducted.
Just so you know!

Must be quite old – it’s still references the DLO rather than DE&S (soon to GoCo).