39-01 Instructional exposition (textbooks, tutorial papers, etc.)

39-02 Research exposition (monographs, survey articles)

39-03 Historical (must also be assigned at least one classification number from Section 01)

39-04 Explicit machine computation and programs (not the theory of computation or programming)

39-06 Proceedings, conferences, collections, etc.

39Axx Difference equations {For dynamical systems, see <a href="#code:37-XX">37-XX</a>; for dynamic equations on time scales, see <a href="#code:34N05">34N05</a>}

39A12 Discrete version of topics in analysis

39A13 Difference equations, scaling ($q$-differences) [See also <a href="#code:33Dxx">33Dxx</a>]

39A20 Multiplicative and other generalized difference equations, e.g. of Lyness type

39A22 Growth, boundedness, comparison of solutions

39A33 Complex (chaotic) behavior of solutions

39A70 Difference operators [See also <a href="#code:47B39">47B39</a>]

39A99 None of the above, but in this section

39Bxx Functional equations and inequalities [See also <a href="#code:30D05">30D05</a>]

39B12 Iteration theory, iterative and composite equations [See also <a href="#code:26A18">26A18</a>, <a href="#code:30D05">30D05</a>, <a href="#code:37-XX">37-XX</a>]

39B22 Equations for real functions [See also <a href="#code:26A51">26A51</a>, <a href="#code:26B25">26B25</a>]

39B32 Equations for complex functions [See also <a href="#code:30D05">30D05</a>]

39B42 Matrix and operator equations [See also <a href="#code:47Jxx">47Jxx</a>]

39B52 Equations for functions with more general domains and/or ranges

39B55 Orthogonal additivity and other conditional equations

39B62 Functional inequalities, including subadditivity, convexity, etc. [See also <a href="#code:26A51">26A51</a>, <a href="#code:26B25">26B25</a>, <a href="#code:26Dxx">26Dxx</a>]

39B72 Systems of functional equations and inequalities

39B82 Stability, separation, extension, and related topics [See also <a href="#code:46A22">46A22</a>]

39B99 None of the above, but in this section

40-00 General reference works (handbooks, dictionaries, bibliographies, etc.)