A legal entity that can act as: data supplier, operational centre, data node, data centre, …

Analysis Centre

Centre that analyses GNSS observations, or derived GNSS products, and makes the resulting products (e.g. positions, time series, velocity and strain rate) available at to EUREF or EPOS.

Data Centre (DC)

Physical location of the GNSS station observation/navigation data.

Data Supplier

The Data Supplier (see also Station Owner or Responsible Agency) has the legal rights to distribute the data of a GNSS stations to a third party. The Data Supplier has paid for the GNSS equipment and has the right to stop its operation. For EPOS stations, the Data Supplier signs the EPOS-GNSS Data Supplier Letter. In the site log, the Data Supplier is inserted in section 12 "Responsible Agency". In GeodesyML it is inserted in the field "siteOwner".

Data Repository

Identical to Data Centre.

DOMES Number

Unique number (e.g. 10003M008) attributed by the IERS (International Earth Rotation and Reference System Service) to the reference point of a GNSS station. It can be a physical marker (e.g. a bold on the ground) or a virtual marker (e.g. centre-bottom of the GNSS antenna). The DOMES number has to be requested from the ITRF web site.


Geodesy Markup Language, a new GML application schema (see developed by the IGS to describe how geodetic data and metadata can be defined and transferred in XML format. This XML-based standard includes objects like antenna, receiver, cable, adjustments etc.

GNSS Station

A GNSS system, consisting of GNSS equipment (antenna, receiver and associated hardware and software) described in a GNSS site log file (that should in fact be called station log for consistency).


Software package “Metadata Management and distribution system for Multiple GNSS Networks”

M3G Associated Agency Form

On-line form within M3G, which allows to input information about the agencies involved in the operation of the stations managed by an OC. These agencies can act as on-site contact, stations owners, network managers, … .


Portal where M3G is running and Operational Centers maintain the GNSS station metadata:

M3G Registered Agency

Agency that maintains station metadata in M3G. Identical to Operational Centre.

M3G Station Metadata Form

On-line form within M3G, which allows to input and display a GNSS site log.

M3G User Agency Form

On-line form within M3G, which allows to input information about the OC and the stations whose metadata it managers. After saving the form, it exports an Operational Centre form.

Marker Name

Identical to the 4-character station ID.

Marker Number

Identical to the DOMES number.

Marker Long Name

Identical to the Nine-letter (unique) station identification, uppercase, coming from RINEX 3 format description. The first 4 letters are the Station Marker and the last three the ISO country code. The middle two digits relate to antenna/receiver at the station. Example: "SOPH00FRA”.

On-site Point of Contact

Local point of contact at a GNSS station, indicated in Section 11 of the site log. In GeodesyML this information is entered in the field "siteContact".

Operational Centre (OC)

The OC is responsible for maintaining the station metadata in M3G. Each OC gets an account in M3G and becomes a "Registered Agency" in M3G. For EPOS stations, the EPOS-GNSS Data Supplier indicates for each station which agency will be acting as OC. In the site log, the contact person of the Operational Centre that updated the site log is entered in the field "Prepared by". In GeodesyML, this information is inserted in the field "siteMetaDataCustodian".

Operational Centre Form

Text-based file (e.g. ROB.OC) that describes the information for one Operational Centre about

  • Agency acting as Operational Centre
  • Contact information for the Operational Centre
  • Stations whose metadata are maintained by the OC

Responsible Agency

Identical to Station Owner or Data Suppplier


Standard Receiver Independent Exchange format for exchanging file-based GNSS observables, navigation data, and meteorological data. Several versions exist.


Geographical physical Location where one or more GNSS stations and other Earth Science equipment are installed.

Site Log

Text-based description description of the metadata of a GNSS station. The format is maintained by the International GNSS Service (IGS), see

Site Metadata Custodian

Identical to Operational Centre

Station 4-character ID

Four printable ASCII characters (usually case-insensitive alphanumeric plus underscore) which traditionally have been used to designate a GNSS station and the first 4 characters of its RINEX data file name. Example: "CASC". In cases where multiple GNSS receivers are split off from the same antenna, each GNSS receiver is considered a separate station and a different 4-character ID needs to be defined. The station 4-character ID is not guaranteed to be unique, although in this phase (until full move to station 9-character ID), this must be imposed.

Station 9-character ID

New station ID to be used in replacement of the station 4-character ID. The 9-character ID follows the RINEX 3 station naming conventions. The first 4 characters are the station 4-character ID and the last three the ISO country code. The middle two digits (0-9) relate to monument (or marker)/receiver. Until full move to station 9-character ID, the antenna number and receiver number are always "0" and there is a one-to-one relation between the station 4-character ID and its 9-character ID. Example: "CASC" and “CASC00PRT”.

Station Log

Identical to site log

Station Owner

Identical to Data Supplier or Responsible Agency

Tracking Station (TS)

Permanent GNSS tracking receivers and antennae

Data Gateway (DGW)

Provides access to the metadata and data from the EPOS-GNSS stations.

Data Node (DN)

Virtualization layer on top of one (or more) Data Centre(s). Using the Glass software, the Data Node makes the GNSS station data at Data Centers (or data repositories) globally discoverable at the EPOS-GNSS data gateway and also locally at the data local node

Data Node Manager (DNM)

This contact is responsible for the operational running of a Glass Node.

Data Node Service Contract (DNSC)

Description of the service supplied by a center node. This contract specifies the stations and types of data it may consider accepting in terms of its geographical extent and other attributes.

Data Supplier Letter

Letter to be signed by a Data Supplier (or station owner) and provided to the M3G-bureau. It gives EPOS the permission to distribute its GNSS data.

EPOS Central Hub

Main gateway/portal of the EPOS project. This portal as well as providing access to GNSS data and products allow access to multidisciplinary data, products (including synthetic data from simulations, processing and visualization tools), and services to different stakeholders, including users from the scientific community and industrial partners. EPOS:


Integrated software package that is deployed in a GNSS infrastructures contributing to EPOS in order to manage GNSS data and metadata.

Product Portal/Gateway

Provides access to GNSS products computed in the scope of the EPOS. Products are made available for download to users in various formats.