In Tcl, these strings are taken as logical false:

   * '''0''' (the canonical form, like in C)
   * '''no'''
   * '''off'''
   * '''false'''

Also allowed are case-insensitive equivalents (i.e., "FaLSe") as well as the unambiguous abbreviations ''n'' for no, ''of'' for off (but not just '''o'''!), and ''f'', ''fa'', ''fal'' and '''fals''' for false.  Other numeric forms equivalent to 0 (i.e., ''0.0'', ''0x0'', ''0e0'', or ''0e#'' or ''0e-#'').

See also [true], '''[string is] false'''.

<<categories>> Language