Logical Unit 6.2 is an IBM-originated communications protocol specification dating from 1974, and is part of IBM's Systems Network Architecture (SNA).
In 1986, Bruce Compton, Manager of Office Systems and Technology with General Electric, said: LU 6.2 means I don't have to write the software communications interfaces.
I can use the LU 6.2 standard to pass files between those devices, and I don't have to worry about things like block checking and clock.
[1] Some examples of non-IBM products which implemented the SNA stack including LU6.2 are: Microsoft Host Integration Server, and NetWare for SAA.
IBM later defined the Common Programming Interface for Communications (CPIC) API which would eventually become widely implemented.