The Torsion-Bending Constant of open sections is of great importance in the calculation of buckling loads under compression of struts failing in the torsional or torsional-flexural mode. It involves computation of the warping of the cross section and misunderstandings arising out of terminology and notation often mislead the users of the formulae. The purpose of this note is to clarify the terminology without going into proofs as well as presenting the equations required using a consistent notation.