L6 was the short name of the Bell Telephone Laboratories' Low-Level Linked List Language developed by Ken Knowlton. Its main difference from other list processing languages was that it allowed the user to get much closer to machine code in order to write faster-running programs, to use storage more efficiently and to build a wider variety of linked data structures.
One feature was that the user could define a set of base fields called bugs that could point at part of the list structure and changes could be made relative to the bug. The programmer could reposition the bugs so that different parts of the structure could be processed. A full description of L6 appears in Ken Knowlton's CACM paper.
In 1966, Ken also produced two 16mm films using BEFLIX on the SC4020 Part 1 and Part2 which describe L6. Two shots from Part 1:
A bug in use
