customize-package-emacs-version-alist

customize-package-emacs-version-alist is a variable defined in `cus-edit.el'.
Its value is shown below.

Documentation:
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:

(PACKAGE (PVERSION . EVERSION)...)

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.

Value:

((ReST
  ("1.0.0" . "24.3")
  ("1.1.0" . "24.3")
  ("1.2.0" . "24.3")
  ("1.2.1" . "24.3")
  ("1.3.0" . "24.3")
  ("1.3.1" . "24.3")
  ("1.4.0" . "24.3"))
 (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"))
 (Org
  ("6.21b" . "23.1")
  ("6.33x" . "23.2")
  ("7.8.11" . "24.1")
  ("7.9.4" . "24.3")
  ("8.2.6" . "24.4")))