Выражение встречается в следующем контексте: For preliminary GD&T releases, feature control frames are to be used with X.X in the tolerance field along with a description below the feature control frame to denote that the feature is critical but the tolerance has not been established. These points are used at part buy-off to verify the repeatability and dimensional integrity of the part. They include any Body Systems Audit points (i.e. gap, flush, seal margin, etc.) as well as other critical product features such as locating holes, critical mating surfaces, and/or critical trim edges.
Вообще речь идет об описании системы автоматизированного проектирования.

Заранее большое спасибо