Some classes define an intrinsic order amongst instances. This includes numbers, sequences (in particular, strings), and words.

<=> ( obj1 obj2 -- <=> )

>=< ( obj1 obj2 -- >=< )

compare ( obj1 obj2 quot -- <=> )

invert-comparison ( <=> -- >=< )

The above words output order specifiers.
Ordering specifiers

Utilities for comparing objects:

after? ( obj1 obj2 -- ? )

before? ( obj1 obj2 -- ? )

after=? ( obj1 obj2 -- ? )

before=? ( obj1 obj2 -- ? )

Minimum, maximum, clamping:

min ( obj1 obj2 -- obj )

max ( obj1 obj2 -- obj )

clamp ( x min max -- y )

Out of the above generic words, it suffices to implement <=> alone. The others may be provided as an optimization.
Linear order example

See also
Sorting sequences