# Commission Implementing Regulation (EU) 2019/838 of 20 February 2019 on technical specifications for vessel tracking and tracing systems and repealing Regulation (EC) No 415/2007, Division 3.5.2: Application identifier for Inland AIS Application Specific Messages

Extent: E+W+S+N.I.

The application specific messages consist of the AIS Class A mobile stations framework according Recommendation ITU-R M.1371 (message ID, repeat indicator, source ID, destination ID), the Application Identifier (AI = DAC + FI) and the data content (variable length up to a given maximum).
The 16-bit application identifier (AI = DAC + FI) consists of the following elements:
(a) 10-bit designated area code (DAC): international (DAC = 1) or regional (DAC > 1);
(b) 6-bit function identifier (FI) — allows for 64 unique application specific messages.
For the European harmonized Inland AIS Application Specific Messages the DAC ‘200’ is used.
In addition national (regional) DAC may be used in local ASM e.g. test pilots. Nevertheless it is strongly recommended to avoid the usage of regional ASM.

---
Source: https://www.legislation.gov.uk/eur/2019/838/annex/division/3/division/3.5/division/3.5.2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2019-838/annex/division-3/division-3.5/division-3.5.2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.