| 03C05 | Equational classes, universal algebra [See also 08Axx, 08Bxx, 18C05] |
| 03C07 | Basic properties of first-order languages and structures |
| 03C10 | Quantifier elimination, model completeness and related topics |
1 | 03C13 | Finite structures [See also 68Q15, 68Q19] |
| 03C15 | Denumerable structures |
| 1 | 03C20 | Ultraproducts and related constructions |
| 03C25 | Model-theoretic forcing |
| 03C30 | Other model constructions |
| 03C35 | Categoricity and completeness of theories |
| 1 | 03C40 | Interpolation, preservation, definability |
| 1 | 03C45 | Classification theory, stability and related concepts [See also 03C48] |
| 03C48 | Abstract elementary classes and related topics [See also 03C45] |
| 03C50 | Models with special properties (saturated, rigid, etc.) |
| 03C52 | Properties of classes of models |
| 03C55 | Set-theoretic model theory |
| 03C57 | Effective and recursion-theoretic model theory [See also 03D45] |
| 5 | 03C60 | Model-theoretic algebra [See also 08C10, 12Lxx, 13L05] |
| 2 | 03C62 | Models of arithmetic and set theory [See also 03Hxx] |
| 03C64 | Model theory of ordered structures; o-minimality |
| 03C65 | Models of other mathematical theories |
| 03C68 | Other classical first-order model theory |
| 03C70 | Logic on admissible sets |
| 03C75 | Other infinitary logic |
| 03C80 | Logic with extra quantifiers and operators [See also 03B42, 03B44, 03B45, 03B48] |
| 03C85 | Second- and higher-order model theory |
| 1 | 03C90 | Nonclassical models (Boolean-valued, sheaf, etc.) |
| 03C95 | Abstract model theory |
| 1 | 03C98 | Applications of model theory [See also 03C60] |
| 03C99 | None of the above, but in this section |