man, Dpkg::Vendor: Document the format of the origin filename

Prompted-by: Martin Michlmayr <tbm@debian.org>

debian/changelog

@@ -93,6 +93,7 @@ dpkg (1.18.5) UNRELEASED; urgency=medium
       the template symbol files are described in dpkg-gensymbols(1).
       Closes: #795163
     - Update field requirements of control file formats to match dpkg reality.
+    - Document the format of the origins filename in deb-origin(5).
 
   [ Updated programs translations ]
   * Portuguese (Miguel Figueiredo).

man/deb-origin.5

@@ -23,13 +23,22 @@ deb\-origin \- Vendor-specific information files
 .BI /etc/dpkg/origins/ filename
 .SH DESCRIPTION
 The files in \fB/etc/dpkg/origins\fP can provide information about
-various vendors who are providing Debian packages. They contain a
-number of fields, or comments when the line starts with \(oq\fB#\fP\(cq.
+various vendors who are providing Debian packages.
+
+They contain a number of fields, or comments when the line starts with
+\(oq\fB#\fP\(cq.
 Each field begins with a tag, such as \fBVendor\fP or \fBParent\fP,
 followed by a colon and the body of the field. Fields are delimited
 only by field tags. In other words, field text may be multiple lines
 in length, but the tools will join lines when processing the body of
 the field.
+
+The file should be named according to the vendor name.
+The usual convention is to name the vendor file using the vendor name
+in all lowercase, but some variation is permitted.
+Namely, spaces are mapped to dashes (\(oq\fB\-\fP\(cq), and the file
+can have the same casing as the value in \fBVendor\fP field, or it can
+be capitalized.
 .SH FIELDS
 .TP
 .BR Vendor: " \fIvendor-name\fP (required)"

scripts/Dpkg/Vendor.pm

@@ -61,7 +61,10 @@ the relationship by listing the base distribution in the Parent field:
 
   Parent: Debian
 
-The file should be named according to the vendor name.
+The file should be named according to the vendor name. The usual convention
+is to name the vendor file using the vendor name in all lowercase, but some
+variation is permitted. Namely, spaces are mapped to dashes ('-'), and the
+file can have the same casing as the Vendor field, or it can be capitalized.
 
 =head1 FUNCTIONS
 
@@ -199,6 +202,10 @@ New function: get_vendor_dir().
 
 Mark the module as public.
 
+=head1 SEE ALSO
+
+deb-origin(5).
+
 =cut
 
 1;