Variable: customize-package-emacs-version-alist

Alist mapping versions of a package to Emacs versions.
We use this for packages that have their own names, but are released
as part of Emacs itself.

Each elements looks like this:


Here PACKAGE is the name of a package, as a symbol. After
PACKAGE come one or more elements, each associating a
package version PVERSION with the first Emacs version
EVERSION in which it (or a subsequent version of PACKAGE)
was first released. Both PVERSION and EVERSION are strings.
PVERSION should be a string that this package used in
the :package-version keyword for `defcustom', `defgroup',
and `defface'.

For example, the MH-E package updates this alist as follows:

(add-to-list 'customize-package-emacs-version-alist
'(MH-E ("6.0" . "22.1") ("6.1" . "22.1")
("7.0" . "22.1") ("7.1" . "22.1")
("7.2" . "22.1") ("7.3" . "22.1")
("7.4" . "22.1") ("8.0" . "22.1")))

The value of PACKAGE needs to be unique and it needs to match the
PACKAGE value appearing in the :package-version keyword. Since
the user might see the value in a error message, a good choice is the official name of the package, such as MH-E or Gnus.