format-patch Metadata
=====================

Background
----------

The current format-patch data lacks a way to express general metadata that may
be useful to synthesize the original commit more accurately.  This may be
helpful to emit patches as a transport for actual commits between machines in a
case where bundles are not practical, such as a mailing list.

Syntax
------

The syntax contains three space-separated components: a field name, an encoding,
and field data.

The field name contains no spaces.  Values without an `@` are specified below or
by a future version of Git.  Values containing an `@` followed by a domain are
specified by that domain owner, much as algorithm names in the SSH protocol.

The encoding is either `plain`, in which case the field data is a literal string
with no spaces, or `base64`, in which case the field data is one or more
space-separated base64 items, which when interpreted have all spaces stripped
and are then encoded.  This allows fields to be specified that contain octets
which are not valid in or which are too long to specified in an RFC 5322 header
unencoded.

Fields
------

base-commit-sha1::
	This specifies the base commit for this patch using a SHA-1 object ID.
base-commit-sha256::
	This specifies the base commit for this patch using a SHA-256 object ID.
	appropriate.
gpgsig-sha1::
	This specifies a signature for this patch using the SHA-1 format, as specified
	in the `gpgsig` header.
gpgsig-sha256::
	This specifies the base commit for this patch using the SHA-256 object ID, as
	specified in the `gpgsig-sha256` header.
mailmap-author::
	This specifies the mailmap entry to associate with the email address or other
	identifier in the `From:` header.

Examples
--------

----
X-Git-Metadata: base-commit-sha1 plain da39a3ee5e6b4b0d3255bfef95601890afd80709

X-Git-Metadata: gpgsig-sha256 base64
  LS0tLS1CRUdJTiBTU0ggU0lHTkFUVVJFLS0tLS0KYmxhaCBibGFoIGJsYWgKLS0tLS1FTkQgU1NI
  IFNJR05BVFVSRS0tLS0tCg==

X-Git-Metadata: foo@example.com plain quux
----