[Thomas_AR]

Ok, that seams to do the trick - perhaps there are for sure things to improve?

I added simple the Tag "MAS" (Multi Author Series) to "tags", than using:

program:

# return separator+authors if no Multi Autor Serie (MAS) is found, or return empty
various_authors=in_list(
	field('tags'),
	'&',
	'MAS',
	'',
	 strcat(' - ', field('authors'))
);
end_template=template('{series_index:0>4s| | - }{title} - {authors}');

start_template=test(
	field('series'),
	strcat(
		'_ ',
		field('series'),
		various_authors
	),
	field('authors')
);

strcat(start_template, '/', end_template);

..it seams to work as expected.

Just saw that there is a DC: tag which is not used in Calibre. DC:type This would be perfect for my goal.

http://www.idpf.org/epub/301/spec/ep...l#sec-pub-type

I know its epub 3.x, but should do it in case of using it for a templates.
Any chance to add this DC: type column into the Tag-Editor?