The American Civil War took place in the southern United States.
In telecommunication , a standard test tone is a pure tone with a standardized level generally used for level alignment of single links and of links in tandem .. telecommunication. telecommunication. pure tone. pure tone. level alignment. level alignment. tandem. tandem. For standardized test signal levels and frequencies , see MIL-STD-188-100 for United States Department of Defense -LRB- DOD -RRB- use , and the Code of Federal Regulations Title 47 , part 68 for other Government agencies .. MIL-STD-188. MIL-STD-188. United States Department of Defense. United States Department of Defense. Code of Federal Regulations. Code of Federal Regulations. part 68. part 68