S57 Chart Service From An Renc; Introduction; Permits; Product List - Furuno FEA-2107-BB Operator's Manual

8.6

S57 Chart Service from an RENC

8.6.1

Introduction

Before you can use an RENC service, you have to be authorized as a customer of an RENC. To be authorized you
have to contact an official distributor (chart agent) of RENC. Then, the following services are available:
8.6.2

Permits

Permits are used to control the permission to use a chart. A permit in RENC security is connected to an edition.
Permits also include the expiry date. The expiry date of a permit controls the ENC to SENC conversion. If the issue
date of a chart or update is older or equal to the permit expiry date, then the system can convert an ENC into the
SENC. There are no viewing time limits as used in some other security systems such as ARCS. The operator has a
right to view a chart forever and more over he has a right to convert a chart from its ENC format into the SENC
forever.
An RENC can issue permits in two formats:
• "*.pmt" format. This format does not include the applicable chart edition nor does it include applicable
permit type.
• PERMIT.TXT format. This format includes the applicable chart edition as well as applicable permit type.
Both permit formats are fully operational, but the older "*.pmt" format creates confusion because it cannot support
the operator when chart edition changes.
The system display warnings associated with expiry date. Examples are "will expire" warning 30 days before the
expiry date and "have expired" after the expiry date. These warnings are relevant only for Subscription permits.
Only the new PERMIT.TXT format supports the system to suppress irrelevant warnings associated with expiry date.
8.6.3

Product list

A Product List is maintained by an RENC. You can retrieve the Product List from an RENC via telecommunications
or you can load it from the CD ROM of an RENC. This list contains an up-to-date list of available charts and their
edition/update status in an RENC. When you load a CD ROM or use telecommunications to receive a Product List
from an RENC, the ECDIS checks the issue date of the Product List. If the issue date indicates a newer Product List,
then it is copied into the ECDIS. If the issue date indicates an older Product List, then ECDIS shows a notice to the
operator that newer Product List is already loaded.
8.6.4

Authentication

Normally the authentication process is invisible to the operator. Only if the authentication fails, then the operator
gets an appropriate notice. From a operator point of view, the authentication is similar to the CRC checksum test. If
the CRC checksum test or authentication fails, then the chart is unusable.
Authentication uses a private key and a public key. A digital signature associated with each chart contains a private
key. A public key is stored in the ECDIS and it is truly public. RENC may publish a new public key. This public
key will be available as text by fax, by post, by front page of a newspaper, etc. and as a text file, for example,
PRIMAR.PUB.
8. Vector Chart Material
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