In a paper of [P. Michor][1], it was shown that *Emb(M,N)* is a smooth principal *diff(M)*-bundle, *M* and *N* are smooth locally compact manifolds provided *dim M < dim N*. My question is why there is a restriction on the dimensions. Does anyone know a reference for the result when *dim M = dim N* ? Thanks in advance [1]: http://www.mat.univie.ac.at/~michor/mf-smo-3.pdf