54-00 General reference works (handbooks, dictionaries, bibliographies, etc.)

54-01 Instructional exposition (textbooks, tutorial papers, etc.)

54-02 Research exposition (monographs, survey articles)

54-03 Historical (must also be assigned at least one classification number from Section 01)

54-04 Explicit machine computation and programs (not the theory of computation or programming)

54-06 Proceedings, conferences, collections, etc.

54A05 Topological spaces and generalizations (closure spaces, etc.)

54A10 Several topologies on one set (change of topology, comparison of topologies, lattices of topologies)

54A20 Convergence in general topology (sequences, filters, limits, convergence spaces, etc.)

54A25 Cardinality properties (cardinal functions and inequalities, discrete subsets) [See also <a href="#code:03Exx">03Exx</a>] {For ultrafilters, see <a href="#code:54D80">54D80</a>}

54A35 Consistency and independence results [See also <a href="#code:03E35">03E35</a>]

54A40 Fuzzy topology [See also <a href="#code:03E72">03E72</a>]

54A99 None of the above, but in this section

54B17 Adjunction spaces and similar constructions

54B30 Categorical methods [See also <a href="#code:18B30">18B30</a>]

54B40 Presheaves and sheaves [See also <a href="#code:18F20">18F20</a>]

54B99 None of the above, but in this section

54Cxx Maps and general types of spaces defined by maps

54C10 Special maps on topological spaces (open, closed, perfect, etc.)

54C30 Real-valued functions [See also <a href="#code:26-XX">26-XX</a>]

54C35 Function spaces [See also <a href="#code:46Exx">46Exx</a>, <a href="#code:58D15">58D15</a>]

54C40 Algebraic properties of function spaces [See also <a href="#code:46J10">46J10</a>]

54C50 Special sets defined by functions [See also <a href="#code:26A21">26A21</a>]

54C55 Absolute neighborhood extensor, absolute extensor, absolute neighborhood retract (ANR), absolute retract spaces (general properties) [See also <a href="#code:55M15">55M15</a>]

54C56 Shape theory [See also <a href="#code:55P55">55P55</a>, <a href="#code:57N25">57N25</a>]