Definition
COUPLED SCHEDULING (CS)/ EXTENDED METERING (XM)
Adds additional Constraint Satisfaction Points for metered aircraft along their route. This provides the ability to merge flows upstream from the meter fix and results in a more optimal distribution of delays over a greater distance from the airport, increased meter list accuracy, and more accurate delivery to the meter fix.
Source: FAA Pilot/Controller Glossary (verbatim from the Federal Aviation Regulations).