This document lists changes to the Mathematics Subject Classification at the 2-digit level. In addition, there are conversion tables for sub-level changes.

1980: 02 changed to 03 and 04

- up to 1979, 02 was used to classify logic and set theory
- from 1980 to 1999, 03 was used for logic and 03 or 04 for set theory

2000: 04 incorporated into 03

- from 1980 to 1999, 03 was used for logic and 03 or 04 for set theory
- from 2000, 03 has been used for logic and set theory

- up to 1961, 09 was used to classify some items in algebra;
- in 1962, 09 was discontinued
- since 1962, one or more sections of 08, 12--20 have been used to classify algebra

- up to 1984, 10 was used to classify number theory
- since 1985, 11 has been used to classify number theory

- since 2000, 37 has been used to classify dynamical systems (previously classified primarily in 58) and ergodic theory (previously classified in 28) have mainly been classified in 37

- up to 1956, 48 was used to classify geometry
- in 1957 and 1958, both 48 and 50 were used to classify geometry
- from 1959 to 1979, 50 was used to classify geometry
- since 1980, 51 has been used to classify geometry

- up to 1999, 73 was used to classify mechanics of solids
- since 2000, 74 has been used to classify mechanics of solids

- since 2000, 91 has been used to classify game theory and mathematical economics (previously classified in 90), and social and behavioral sciences (previosuly classified in 92)

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