51-XX Geometry,

• 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 be assigned at least one classification number from 01-XX)
• 51-04 Explicit machine computation and programs (not the theory of computation or programming)
• 51-06 Proceedings, conferences, collections, etc.
• 51Axx Linear incidence geometry
• 51Bxx Nonlinear incidence geometry
• 51C05 Ring geometry (Hjelmslev, Barbilian, etc.)
• 51Dxx Geometric closure systems
• 51Exx Finite geometry and special incidence structures
• 51Fxx Metric geometry
• 51G05 Ordered geometries (ordered incidence structures, etc.)
• 51Hxx Topological geometry
• 51Jxx Incidence groups
• 51Kxx Distance geometry
• 51Lxx Geometric order structures, see also {53C75}
• 51Mxx Real and complex geometry
• 51Nxx Analytic and descriptive geometry
• 51P05 Geometry and physics (should also be assigned at least one other classification number from Sections 70--86)