In the world of electronics design and manufacturing, few things are as critical—and sometimes as confusing—as part identification. Whether you are reverse-engineering a legacy board or verifying components for a new production run, stumbling upon a cryptic marking like can lead to a rabbit hole of research.

: This is a UL 94 flammability rating . It indicates that the plastic material used in the PCB is self-extinguishing within 10 seconds after a flame is removed, with no flaming drips allowed.

Materials undergo vertical flame testing.