Export Control Classification Number

The Export Control Classification Number (ECCN) refers to "[t]he numbers used in Supplement No. 1 to part 774 of the EAR and throughout the EAR. The Export Control Classification Number consists of a set of digits and a letter. Reference §738.2(c) of the EAR for a complete description of each ECCN’s composition."

Source
U.S. Export Administration Regulations, Part 772 (15 C.F.R. §772.1).