  After a brief review of the role three-nucleon forces play in the few-nucleon
systems, the chiral-perturbation-theory approach to these forces is discussed.
Construction of the (nominal) leading- and subleading-order Born terms and
pion-rescattering graphs contributing to two-pion-exchange three-nucleon forces
is reviewed, and comparisons are made of the types of such forces that are used
today. It is demonstrated that the short-range $c$-term of the Tucson-Melbourne
force is unnatural in terms of power counting and should be dropped. The class
of two-pion-exchange three-nucleon forces then becomes rather uniform.
