34A05 Explicit solutions and reductions
34A09 Implicit equations, differential-algebraic equations [See also 65L80]
34A12 Initial value problems, existence, uniqueness, continuous dependence and continuation of solutions 
34A25 Analytical theory: series, transformations, transforms, operational calculus, etc. [See also 44-XX]
34A26 Geometric methods in differential equations
34A30 Linear equations and systems, general
34A34 Nonlinear equations and systems, general
34A35 Differential equations of infinite order
34A36 Discontinuous equations
34A37 Differential equations with impulses
34A40 Differential inequalities [See also 26D20]
34A45 Theoretical approximation of solutions {For numerical analysis, see 65Lxx}
34A55 Inverse problems  
34A60 Differential inclusions [See also 49J24, 49K24]
34A99 None of the above, but in this section