7f33ac1a_ecp_cc__Value_Notes
[Part] C12 [Size/#] 1206 [Value/Notes] 
This spot connects the tube's internal shield to ground. Some people ignore this, some use a jumper, and some use a small ceramic cap. If you use a cap, 0.1uF ceramic is probably good. A jumper is fine too.
ecp.cc
Value/Notes