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

Changes to the Mathematics Subject Classification at the 2-digit Level

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

1962: 09 discontinued

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

1985: 10 changed to 11

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

2000: 28, 58 reconfigured into 58, 37 and 28

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

1980: 50 changed to 51

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

2000: 73 changed to 74

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

2000: 90, 92 reconfigured to 90, 91 and 92

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