BRA and KET: String Interpolation in AmigaDOS | datagubbe.se

By default, the parser does string interpolation using the characters < (less than) and > (greater than). The cleverness of this is debatable: these characters are also used for I/O redirection, which can quickly make things confusing. Luckily, the parser also accepts the directives .BRA and .KET, each followed by a single character, which lets the programmer override the default interpolation characters. The terms BRA and KET are most likely borrowed from Dirac notation.