Why is LaTeX replacing 2010 for the math subject classification with 1991?

Question

I am trying to compile a .tex document and convert it to PDF where I used the command:

\subjclass[2010]{***(primary), and ***(secondary)} 

(*** correspond to some suitable number from the subject classification).

I used

\documentclass{amsart}
\usepackage{amscd,amsmath,amssymb,amsthm,amsfonts,epsfig,graphics}

While compiling the document, the compiler replaces 2010 by 1991 automatically (it also tells me so) and in the PDF output, I also see 1991 subject classification, not 2010 subject classification!

Could you inform me why is this happening? What should I do to get the 2010 subject classification?

Finally the journal where the paper is accepted is asking to confirm that the authors use 2010 subject classification. By any chance, do you think they accept an older classification written at the footnote? (I know the last one is a bad question, but just in the worst case!)

Answer 1

The class checks that the classification is known by checking the internal macro

\@namedef{subjclassname@2010}{%
  \textup{2010} Mathematics Subject Classification}

If you are getting a warning that 2010 is not known, then this macro is presumably not defined in the class because you have an old copy of amsart, I copied the above from

\ProvidesClass{amsart}[2009/07/02 v2.20.1]

Your log file (or output from \listfiles should show which version you have.