expr comparison operator; returns either a 1 or a 0, depending on whether the first argument is greater than the second.
$ tclsh8.5 % tcl::mathop::> 1 2 0 % tcl::mathop::> 2 1 1 % tcl::mathop::> 2 2 0 % tcl::mathop::> a b 0 % tcl::mathop::> b a 1 % tcl::mathop::> abc 123 1 % tcl::mathop::> abc abcd 0