  We propose a new description of dynamics of autonomous mechanical systems
which includes the momentum-velocity relation. This description is formulated
as a variational principle of virtual action more complete than the Hamilton
Principle. The inclusion of constraints in this description is the main topic
of the present note. We give examples and models of constraints in variational
formulations of statics and dynamics of autonomous systems. Holonomic
constraints are usually interpreted as restrictions on configurations of a
mechanical system. Nonholonomic constraints are additional restrictions imposed
on velocities. This traditional terminology is not adapted to our concept of
constraints as imposed on virtual displacements and only indirectly affecting
configurations and velocities. Our concept of nonholonomic constraints makes
perfect sense for static systems even if velocities do not appear in the
description of such systems.
