35A05 General existence and uniqueness theorems
35A07 Local existence and uniqueness theorems [See also 35Hxx, 35Sxx]
35A08 Fundamental solutions
35A10 Cauchy-Kovalevskaya theorems
35A15 Variational methods
35A17 Parametrices
35A18 Wave front sets
35A20 Analytic methods, singularities
35A21 Propagation of singularities
35A22 Transform methods (e.g. integral transforms)
35A25 Other special methods
35A27 Microlocal methods; methods of sheaf theory and homological algebra in PDE [See also 32C38, 58J15]
35A30 Geometric theory, characteristics, transformations [See also 58J70, 58J72]
35A35 Theoretical approximation to solutions {For numerical analysis, see 65Mxx, 65Nxx}
35A99 None of the above, but in this section