We study the space Orth∞(L)
of extended orthomorphisms in an Archimedean Riesz space L and its analogies with
the complete ring of quotients of a commutative ring with unit element. It is shown
that for any uniformly complete f-algebra A with unit element, Orth∞(A)
is isomorphic with the complete ring of quotients of A. Furthermore, it is
proved that for any uniformly complete Riesz space L the space Orth∞(L)
is isomorphic to the lateral completion of L. Finally, it is shown that for
any uniformly complete Riesz space L the ring Orth∞(L) is von Neumann
regular.