Since 1. January 2007 there is a new format of ISBN. The new numbers are 13 digit long. Different formats of ISBN are not allowed by the National agency for ISBN as valid. In case of not respecting the new format there can be sanctions for CULS as the publisher.
For further reading on the matter of ISBN please visit the webpage of National Library of Czech Republic.
For information about ISSN please visit web of National Technical Library.