49S99 None of the above, but in this section

51-XX Geometry {For algebraic geometry, see <a href="#code:14-XX">14-XX</a>}

51-00 General reference works (handbooks, dictionaries, bibliographies, etc.)

51-01 Instructional exposition (textbooks, tutorial papers, etc.)

51-02 Research exposition (monographs, survey articles)

51-03 Historical (must also be assigned at least one classification number from Section 01)

51-04 Explicit machine computation and programs (not the theory of computation or programming)

51-06 Proceedings, conferences, collections, etc.

51A05 General theory and projective geometries

51A10 Homomorphism, automorphism and dualities

51A25 Algebraization [See also <a href="#code:12Kxx">12Kxx</a>, <a href="#code:20N05">20N05</a>]

51A30 Desarguesian and Pappian geometries

51A35 Non-Desarguesian affine and projective planes

51A45 Incidence structures imbeddable into projective geometries

51A50 Polar geometry, symplectic spaces, orthogonal spaces

51A99 None of the above, but in this section

51B99 None of the above, but in this section

51Cxx Ring geometry (Hjelmslev, Barbilian, etc.)

51C05 Ring geometry (Hjelmslev, Barbilian, etc.)

51C99 None of the above, but in this section

51D10 Abstract geometries with exchange axiom

51D15 Abstract geometries with parallelism

51D20 Combinatorial geometries [See also <a href="#code:05B25">05B25</a>, <a href="#code:05B35">05B35</a>]

51D25 Lattices of subspaces [See also <a href="#code:05B35">05B35</a>]

51D30 Continuous geometries and related topics [See also <a href="#code:06Cxx">06Cxx</a>]

51D99 None of the above, but in this section

51Exx Finite geometry and special incidence structures

51E05 General block designs [See also <a href="#code:05B05">05B05</a>]

51E12 Generalized quadrangles, generalized polygons

51E14 Finite partial geometries (general), nets, partial spreads

51E20 Combinatorial structures in finite projective spaces [See also <a href="#code:05Bxx">05Bxx</a>]

51E22 Linear codes and caps in Galois spaces [See also <a href="#code:94B05">94B05</a>]