The 2020 revision of the Mathematics Subject Classification (MSC2020) was published earlier this year. It is a joint project of Mathematical Reviews (MR) and zbMATH, which collectively maintain the MSC. Reviewing services, publishers, funding agencies, and other organizations use this alphanumerical classification scheme to categorize items in the mathematical sciences literature.
Every 10 years, MR and zbMATH request input from the mathematics community and generate an updated MSC based on the resulting comments. MSC2020 contains 63 two-digit classifications, 529 three-digit classifications, and 6,006 five-digit classifications, reflecting updates at both the three-digit and five-digit level. It also accounts for data and computation’s ongoing influence on the mathematical sciences, and features general amendments to class descriptions — which are now more useful to those conducting searches both online and via database interfaces.
MR and zbMATH are now using MSC2020 as their respective classification schemes and invite the mathematics community to do the same. MSC2020 is accessible online at msc2020.org. Searchable versions are available from the zbMATH site and the MathSciNet site.