TRON is a debugging command in old dialects of the BASIC programming language. It is an abbreviation of TRace ON. It was used primarily for debugging line-numbered BASIC GOTO and GOSUB statements. In text-mode environments such as the TRS-80 or DOS, it would print the current line number which was being executed, on-screen. In a windowed environment, when the TRON command had been executed, a window would indicate the line number being executed at that instant. This command's opposite is TROFF, or TRace OFF, used to turn off command tracing.