A subset of logistic planning consisting of a four-step process. A. Requirements definition. Requirements for significant items must be calculated at item level detail (i.e., National Stock Number) to support sustainability planning and analysis. Requirements include unit roundout, consumption and attrition replacement, safety stock, and the needs of allies. B. Apportionment. Items are apportioned to the combatant commanders based on a global scenario to avoid sourcing of items to multiple theaters. The basis for apportionment is the capability provided by unit stocks, host-nation support, theater pre-positioned war reserve stocks and industrial base, and continental United States Department of Defense stockpiles and available production. Item apportionment cannot exceed total capabilities. C. Sourcing. Sourcing is the matching of available capabilities on a given date against item requirements to support sustainability analysis and the identification of locations to support transportation planning. Sourcing of any item is done within the combatant commander’s apportionment. D. Documentation. Sourced item requirements and corresponding shortfalls are major inputs to the combatant commander’s sustainability analysis. Sourced item requirements are translated into movement requirements and documented in the Joint Operation Planning and Execution System database for transportation feasibility analysis. Movement requirements for nonsignificant items are estimated in tonnage.