what do the w and k stand for in call letters
Call signs in North America Many countries have specific conventions for classifying call signs by transmitter characteristics and location. The call sign format for radio and television call signs follows a number of conventions. All call signs begin with a prefix assigned by the International Telecommunications Union. For example, the United States has been assigned the following prefixes: "AAA"â€“"ALZ", "K", "N", "W". For a complete list, see international call sign allocations.
Pencil Most manufacturers, and almost all in Europe, designate their pencils with the letters H (commonly interpreted as "hardness") to B (commonly "blackness"), as well as F (usually taken to mean "fineness", although F pencils are no more fine or more easily sharpened than any other grade. Also known as "firm" in Japan[68]). The standard writing pencil is graded HB.[69] This designation might have been first used in the early 20th century by Brookman, an English pencil maker. It used B for black and H for hard; a pencil's grade was described by a sequence or successive Hs or Bs such as BB and BBB for successively softer leads, and HH and HHH for successively harder ones.[70] The Koh-i-Noor Hardtmuth pencil manufacturers claim to have first used the HB designations, with H standing for Hardtmuth, B for the company's location of Budějovice, and F for Franz Hardtmuth, who was responsible for technological improvements in pencil manufacture.[71][72]