--metadata-value

--metadata-value "v1;v2" supplies the values half of a paired injection: the slicer zips each entry from this flag positionally with its counterpart from --metadata-name and writes the resulting key-value pairs as <metadata> elements inside the top-level <model> block of the exported 3MF, between the opening model tag and the <resources> element. The flag has no effect unless --export-3mf is also in use; on any invocation that does not include that export flag the injection path is never reached.

The argument is a C-style semicolon-delimited list. Each semicolon separates one value entry from the next. When the first character of an entry is a double-quote the entry is parsed in quoted mode, which reads until the matching closing double-quote; inside a quoted entry \\ and \" produce a literal backslash or double-quote respectively, and \r / \n produce carriage return or newline. Any entry whose first character is not a double-quote is parsed in unquoted mode and read literally, character by character, until the next semicolon or the end of input — spaces, tabs, backslashes, and newlines in that position are stored verbatim without any special treatment. A trailing semicolon produces one additional empty-string entry, so a;b; yields three entries not two.

At export time the slicer merges the injected pairs into the same map that already holds built-in fields such as the model name, designer, application version, and creation date. Injection happens after those built-in assignments, so supplying a key that matches a built-in field name silently overwrites that built-in value in the output 3MF.

Injected values are XML-escaped when placed into the internal metadata map and then XML-escaped a second time when each map entry is written to the XML stream. As a result, any injected value that contains special XML characters such as <, >, &, ", or ' will appear double-encoded in the output 3MF rather than round-tripping cleanly; such characters in values should be avoided unless the downstream consumer accounts for the double-encoding.