Differential forms on orbifolds with corners

Motivated by symplectic geometry, we give a detailed account of differential forms and currents on orbifolds with corners, the pull-back and push-forward operations, and their fundamental properties. We work within the formalism where the category of orbifolds with corners is obtained as a localization of the category of \'etale proper groupoids with corners. Constructions and proofs are formulated in terms of the structure maps of the groupoids, avoiding the use of orbifold charts. The Fr\'echet space of differential forms on an orbifold and the dual space of currents are shown to be independent of which \'etale proper groupoid is chosen to represent the orbifold.