reftex-default-label-alist-entries

reftex-default-label-alist-entries is a variable defined in `reftex-vars.el'.
Its value is

(amsmath endnotes fancybox floatfig longtable picinpar rotating sidecap subfigure supertab wrapfig listings minted ctable LaTeX)

Documentation:
Default label alist specifications. LaTeX should always be the last entry.
The value of this variable is a list of symbols with associations in the
constant `reftex-label-alist-builtin'. Check that constant for a full list
of options.

You can customize this variable.