This document will assist industry, particularly labelers, as defined under 21 CFR 801.3, and FDA staff in understanding FDA’s requirements for direct marking of devicesfor unique device identification purposes. Under 21 CFR 801.45, “[a] device that must bear a unique device identifier (UDI) on its label must also bear a permanent marking providing the UDI on the device itself if the device is intended to be used more than once and intended to be reprocessed before each use.” This guidance defines some terms used in the Agency’s regulations pertaining to the UDI direct marking requirements, including how FDA interprets the term “intended to be reprocessed” as used in 21 CFR 801.45. For additional background on the UDI system, see the Unique Device Identification System Final Rule, published on September 24, 2013 (78 FR 58786) (the UDI Rule – https://www.gpo.gov/fdsys/pkg/FR-2013-09-24/pdf/2013-23059.pdf ).