AMES Type 80 design intended for all of the northern bases became the Mark II. As early as 1950, the RAF had considered several solutions to the original Phase II GCI requirement, including the Royal Navy's new Type 984 radar, the Army's Orange Yeoman, and an adaptation of the Type 80. By mid-1953, the Air Ministry made the firm decision to use the Type 80-derived Type 81 rather than the other designs. Because the Type 81 spread its signal over a much greater vertical angle, the amount of energy in any one angle was lower. This meant the design would have less range
Less-than sign is used to denote the beginning of a heredoc statement (where OUTPUT is an arbitrary named variable.) In Bash, «<word is used as a "here string", where word is expanded and supplied to the command on its standard input, similar to a heredoc. The less-than sign plus the equals sign (<=) is used for an approximation of the less-than-or-equal-to sign (≤). ASCII does not have a less-than-or-equal-to sign, but Unicode defines it at code point U+2264. In BASIC, Lisp-family languages, and C-family languages (including Java and C++), operator <= means "less than or equal to". In Sinclair BASIC it is