The PGP implementation is usually able to select the proper key to use for signing and decryption, but if you have more than one key, you may need to specify the key id to use.
User ID of your default identity. It defaults to the value returned by ‘(user-login-name)’. You can customize this variable.
User ID of the GnuPG default identity. It defaults to ‘nil’. This overrides ‘pgg-default-user-id’. You can customize this variable.
User ID of the PGP 2.x/6.x default identity. It defaults to ‘nil’. This overrides ‘pgg-default-user-id’. You can customize this variable.
User ID of the PGP 5.x default identity. It defaults to ‘nil’. This overrides ‘pgg-default-user-id’. You can customize this variable.