OR tf1 tf2 (OR tf1 tf2 tf3 ...) outputs TRUE if any input is TRUE, otherwise FALSE. All inputs must be TRUE or FALSE. (Comparison is case-insensitive regardless of the value of CASEIGNOREDP. That is, "true" or "True" or "TRUE" are all the same.) An input can be a list, in which case it is taken as an expression to run; that expression must produce a TRUE or FALSE value. List expressions are evaluated from left to right; as soon as a TRUE value is found, the remaining inputs are not examined. Example: IF OR :X=0 [some.long.computation] [...] to avoid the long computation if the first condition is met.