Are the off-axis terms of WM3D's inertia dyadic correctly signed?

The engineering community lacks a standard sign convention for defining the off-diagonal terms (Products of Inertia) of a body's inertia dyadic. In WM3D, the Products of Inertia are defined with a negative sign, that is:

Under normal circumstances, the user of WM3D should not worry about this definition because the inertia dyadic is automatically calculated for each body and expressed in the Central Inertia tab of the Properties window. In the case where a user wants to manually define the inertia dyadic, the above definition must be used to ensure that the inertia dyadic is consistent with the internal formulation of the system's equations of motion.

See The Definition of Product of Inertia Technical Note for a complete discussion of inertia dyadics.