> 06-XX Order, lattices, ordered algebraic structures

06-00 General reference works (handbooks, dictionaries, bibliographies, etc.)	06-01 Instructional exposition (textbooks, tutorial papers, etc.)	06-02 Research exposition (monographs, survey articles)
06-03 Historical (must also be assigned at least one classification number from Section 01)	06-04 Explicit machine computation and programs (not the theory of computation or programming)	06-06 Proceedings, conferences, collections, etc.
06-99 Order, lattices, ordered algebraic structures (not classified at a more specific level)	06AXX Ordered sets	06BXX Lattices
06CXX Modular lattices, complemented lattices	06DXX Distributive lattices	06EXX Boolean algebras (Boolean rings)
06FXX Ordered structures

06-XX Order, lattices, ordered algebraic structures