R

remaining duration

the amount of time needed to complete an activity.

resource-constrained scheduling

the scheduling of activities in a project with the knowledge of certain resource constraints and requirements. This process adjusts activity scheduled start and finish dates to conform to resource availability and use.

resource leveling

any form of network analysis in which scheduling decisions (start and finish dates) are driven by resource management concerns (for example, limited resource availability or difficult-to-manage changes in resource levels).