pub   4096R/0xAABBD62D0BA66C66 2014-09-02
uid                 [ultimate] Mr. Foo Bar <fourth@example.com>
uid                 [ultimate] Mr. Foo Bar <first@example.com>
uid                 [ultimate] Mr. Foo Bar <third@example.com>
uid                 [ultimate] Mr. Foo Bar <second@example.com>

$ gpg --edit-key 0xAABBD62D0BA66C66
gpg (GnuPG) 1.4.16; Copyright (C) 2013 Free Software Foundation, Inc.
 # irrelevant output removed #
[ultimate] (1). Mr. Foo Bar <fourth@example.com>
[ultimate] (2)  Mr. Foo Bar <first@example.com>
[ultimate] (3)  Mr. Foo Bar <third@example.com>
[ultimate] (4)  Mr. Foo Bar <second@example.com>
gpg> uid 3
[ultimate] (1). Mr. Foo Bar <fourth@example.com>
[ultimate] (2)  Mr. Foo Bar <first@example.com>
[ultimate] (3)* Mr. Foo Bar <third@example.com>
[ultimate] (4)  Mr. Foo Bar <second@example.com>
gpg> primary
[ultimate] (1)  Mr. Foo Bar <fourth@example.com>
[ultimate] (2)  Mr. Foo Bar <first@example.com>
[ultimate] (3)* Mr. Foo Bar <third@example.com>
[ultimate] (4)  Mr. Foo Bar <second@example.com>
gpg> save