[PATCH v4 06/11] doc: interpret-trailers: explain key format

From: Kristoffer Haugsbakk <[email protected]>

A trailer key must consist of ASCII alphanumeric characters and
hyphens *only*. Let’s document it explicitly instead of relying on
readers being conservative and only basing their trailer keys on the
documentation examples.[1]

The previous commit provided us with an appropriate paragraph to
describe the key format.

† 1: Technically they would then miss out on using digits in them since
     all of the example keys just use letters and hyphens

Reported-by: Brendan Jackman <[email protected]>
Signed-off-by: Kristoffer Haugsbakk <[email protected]>
---

Notes (series):
    v2:
    • PS: Reported in https://lore.kernel.org/git/CA+i-1C1DM0CHoFJ0A5CchQg=qDVLi_SSiZqcd0dxsay-Y94WTQ@mail.gmail.com/
    • Remove the “paint by numbers” reference after review (unclear)
    • Add apropos footnote
    • Tweak the paragraph about how we now have a context to describe
      this format
    v1: [had a note about code spelunking (isalnum(3))]

 Documentation/git-interpret-trailers.adoc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-interpret-trailers.adoc b/Documentation/git-interpret-trailers.adoc
index 109059f11ed..fb503cbe952 100644
--- a/Documentation/git-interpret-trailers.adoc
+++ b/Documentation/git-interpret-trailers.adoc
@@ -18,7 +18,8 @@ Add or parse trailer metadata at the end of the otherwise
 free-form part of a commit message, or any other kind of text.
 
 A _trailer_ in its simplest form is a key-value pair with a colon as a
-separator. A _trailer block_ consists of one or more trailers. The
+separator. The _key_ consists of ASCII alphanumeric characters and
+hyphens (`-`). A _trailer block_ consists of one or more trailers. The
 trailer block needs to be preceded by a blank line, where a _blank line_
 is either an empty or a whitespace-only line. For example, in the
 following commit message
-- 
2.54.0.22.g9e26862b904