There seems to be some confusion here about when L-1 was introduced. The chart shows L-1 starting in 1941, but the text references the 1930s, and the AT&T Long Lines page says it started in 1936. 184.108.40.206 (talk) 18:05, 27 August 2009 (UTC)
Where did the data on L2 come from?
I can't find mention of it in BSTJ or other sources. L1, L3, etc fine.... but the L2?