  We investigate local-global principles for multinorm equations over a global
field. To this extent, we generalize work of Drakokhrust and Platonov to
provide explicit and computable formulae for the obstructions to the Hasse
principle and weak approximation for multinorm equations. We illustrate the
scope of this technique by extending results of Bayer-Fluckiger--Lee--Parimala,
Demarche--Wei and Pollio.
