35Sxx Pseudodifferential operators and other generalizations of

35S05  General theory of $\Psi$DO
35S10  Initial value problems for $\Psi$DO
35S15  Boundary value problems for $\Psi$DO
35S30  Fourier integral operators
35S35  Topological aspects: intersection cohomology, stratified
               sets, etc., See also {32C38, 32S40, 32S60, 58G07}
35S50  Paradifferential operators
35S99  None of the above but in this section