Many functions of mregions2 make use of the argument mrgid or return data with the numeric variable MRGID.
But what is this identifier?
This is an unique and persistent identifier of each entry in the Marine Regions Gazetteer. This identifier consists in a URI containing a number, unique for each entry in the Marine Regions Gazetteer. The R package mregions2 uses this number in its functions, and it should be considered a synonym of the standard definition of MRGID.
See the section details for a more in depth definition of the MRGID
Details
From https://marineregions.org/mrgid.php :
Standards
Place names change over time, and the same names may be used for different locations. Available gazetteers may find locations of some marine place names, but a truly global standard for marine place names is lacking. Marine Regions tries to establish for the first time a standardized list of georeferenced marine place names and marine areas. In order to preserve the identity of the marine geographic objects from the database, and to name and locate the geographic resources on the web, we promote the Marine Regions Geographic IDentifier, or the MRGID.
MRGID
The Marine Regions Geographic IDentifier is:
unique by using a URI (Uniform Resource Identifier), it's unique across the internet.
Syntax
http://marineregions.org/mrgid/<number>persistent we will never delete, nor change the concept behind an MRGID
resolvable pointing your client to an MRGID will return - the reply of the webservice call
getGazetteerRecordByMRGID, when using content negotiation (text/turtleorapplication/ld+json) - the webpage of the MRGID, when using a browser
For an identifier to be persistent, it requires the governing body to arrange for the identifier to be available for the long term. Use of the MRGID, as URI and persistent identifier has the commitment of the Flanders Marine Institute, issuing the identifier to maintain the http domain registration, and a strategy for managing the domain and the web servers.