This publication also bears a QC number. This number, QC 680200 is the specification number in the IEC Quality Assessment System for Electronic Components (IECQ). Applies to quartz crystal units the quality of which is assessed on the basis of qualification approval. Prescribes the preferred ratings and characteristics, with the appropriate tests and measuring methods contained in the generic specification IEC 1178-1. Gives general performance requirements to be used in detail specification for quartz crystal units.