20210727 11224300 1.0 TRUE Deep water navigation lines Digitized from Mariners’ Routeing Guide Baltic Sea ISBN 978-3-89871-771-7 (http://www.helcom.dk/map/). The line features are divided in categories, indicated by the the ZONE_TYPE attribute: 0 - Deep water route areas; 1 - Deep water route center line; 4 - Recommended route center; 6 - Traffic separation line; and 7 - Traffic separation scheme. HELCOM