FAQ

M³G stands for Metadata Management and distribution system for Multiple GNSS networks. It consists of a web portal and application program interface (API) developed by the Royal Observatory of Belgium (ROB). Registered agencies can upload, validate, and distribute GNSS station metadata via the M³G website. The GNSS station metadata comprise IGS-style site log files, but also information about e.g., local networks, DOI, station pictures, etc.
M³G has been developed primarily to serve the EPOS and EPN GNSS networks, the EPN densification project, but can serve other GNSS projects and GNSS projects and international, local/national or virtual networks.

• All information included in the so-called IGS site log
• Name of the local/national/virtual/international network or project in which the station is integrated
• Data license of use of the station daily RINEX data set
• Embargo period on the daily RINEX data set
• Station pictures
• Information on the Data Centres and Data Nodes from where the station daily RINEX data can be retrieved
• DOI of the station daily RINEX data set

M³G will update the site log and GeodesyML files on its file server.

• The updated site log and GeodesyML file will automatically flow to the EPN Central Bureau (for EPN or EPN densification stations). It will take up to a few minutes for the updated site log to show up at the EPN Central Bureau web and FTP sites.
• The updated GeodesyML file will automatically flow to the EPOS GNSS Data Gateway (for EPOS stations).
• The updated site log of IGS stations will have to be submitted to IGS by the Station Metadata Maintainer (or the station manager) using the current IGS procedure. M³G will not do this automatically.

M³G provides a REST (Representational state transfer) API to POST, PUT and GET GNSS metadata. For more information, check the API documentation.

To align with FAIR data principles, M³G collects data license of use and embargo period for the daily RINEX data of all stations, but the information is only mandatory for the stations included in the EPOS network. EPOS stations will get the CC BY 4.0 license by default, but this information can be changed by the user.
For more information on the type of data licenses available in M³G, have a look at this FAQ.
For EPN stations, the embargo period will be automatically set to No embargo period and it cannot be changed by the user.

Various types of data license are available in M³G. You can assign a license to your station(s) daily RINEX data after logging in to M³G and clicking (in the agency-specific menu in the top-right of the website menu) on Edit only Data License & Embargo Period or on the general station metadata table Edit all Metadata.

For data openly available without restrictions, and therefore for EPN and EPOS stations, the most natural choices would be:

• CC0 1.0: copy, modify, distribute the data, even for commercial purposes, without asking permission
• CC BY 4.0 (recommended): as CC0 1.0, but one must give credit e.g, via the DOI associated to the station data (if available), and indicate if changes were made to the data

• CC BY-SA 4.0: as CC-BY, but one must redistribute the data under the same license as the original
• CC BY-ND 4.0: as CC-BY, but one cannot redistribute the data if changes were made
• CC BY-NC 4.0: as CC-BY, but one cannot use the data for commercial purposes
• CC BY-NC-SA 4.0: as CC-BY-NC, but one must redistribute the data under the same license as the original
• CC BY-NC-ND 4.0: as CC BY-NC, but one cannot redistribute the data if changes were made

Any agency maintaining GNSS station metadata can obtain a login account for M³G.
By requesting an account, your agency also commits to keep the GNSS station metadata in M³G up to date.
Each registered agency i.e., Station Metadata Maintainer has a unique login/password.
Before registering a new account, please check if your agency has already a M³G account by browsing through the agencies here. Be aware that if the registered agency maintaining the metadata is not the same as the station owner, the station owner has to formally agree that the registered agency maintains its station metadata in M³G. For EPN or EPN densification stations, one does not need to provide M³G with the agreement. However, for EPOS stations, the data owner has to provide information on who is maintaining the metadata in M³G by submitting the EPOS data supplier letter (available here) to the M³G team.

If you only want to retrieve metadata from M³G, you do not need an account.
Logging in to M³G is only required when inserting or updating station metadata and information regarding your agency, third-party agencies, networks, etc.
For more details on how to obtain an account in M³G, have a look at this FAQ.

Your login ID is the unique identification code of your agency. You can find it in the sub-menu Agencies Station Metadata Maintainers under the column M³G login ID (if this column is not visible, click on the button, top left in the table). If your agency is not in the list, you can Register New Account on the Login page. If you do not remember your password, use the button Reset Password.
All the contacts listed in your agency will receive an email from M³G with instructions on how to reset the password. If you do not receive the password reset email, have a look at this FAQ

This might be due to your spam filter or because your email address is not listed in M³G in the contact information related to your agency. In the latter case, you need to contact one of your colleagues included in the contact list and ask to reset the password, log in to M³G, and add your email address to the agency contacts.

Your agency is now considered as Station Metadata Maintainer which can then access and edit information related to

• the stations, e.g. site log, networks/projects to which the station belongs, data licenses, etc.
• all the networks that you have created in M³G
• your own agency and the related contact information
• all agencies (and the corresponding contacts) involved in the operation of your stations i.e., third-party agencies

via the agency-specific tab (click on your agency abbreviation, top right in the website menu bar) and its submenus:

• STATION METADATA:
  • Edit all Metadata
  • Edit only Contact(s) in Site Log(s)
  • Edit only Data License & Embargo Period
  • Add Station(s)
  • Propose Station(s) to Network(s)
• NETWORKS METADATA:
  • Edit Metadata
  • Accept/Reject Station(s)
• AGENCIES METADATA:
  • Edit My Agency Information
  • Edit Third-party Agencies Information

1. Login to M³G
(see FAQ)
2. Go to the agency-specific menu (top right in the website menu bar) and click on Add Station(s)
3. Follow the on-line help at the bottom left of the page (if not visible, click on the )

Note that you can also have a look at the quickstart guide, more specifically the section 4. Set up/add a new station

1. Update the site log (follow the quick-start guide 5. Edit the site log of an existing station) by entering for both antenna AND receiver the date of removal of the equipment (Date Removed) in the most recent (i.e. last) sections
2. Save and submit the site log. By doing so, your station will be automatically labelled as (I)nactive.
3. After submission, you will be redirected to the Edit all Metadata table where you can change the status of your station from (I)nactive to (D)decommissioned by clicking on under the column STATUS

Note that decommissioned stations cannot be removed from the station list of the Station Metadata Maintainers because the metadata of these stations are still valuable for reprocessing historical data.

Send an email to the M³G team listing the station(s) that will be handed over to another agency and

1. provide name and preferred abbreviation of the agency as well as at least one non-personal contact (team name and email address of the team),
2. copy the agency that will take over the maintenance of the station(s) metadata and the station owner (if different from your agency) on in the email

The M³G administrator will make sure that the other agency has a login in M³G and will remove the station(s) you indicated from the list of stations for which you will stop maintaining the metadata. The M³G team will add the stations to the station list of the new Station Metadata Maintainer.

1. If the new Station Owner is not your agency, but a third-party agency, then make sure the new station owner is set up as a Third-Party Agency in M³G
2. Send an email to the M³G team listing the station(s) for which the Station Owner will change and provide name and preferred abbreviation of the old and new Station Owner. You must put the old and new Station Owner (if different from your agency) in copy of this email.

You will need

• Station name (9-char ID, e.g. BRUX00BEL)
• Site log
• Local/national or virtual network to which you want to propose the station (highly recommended).

For more information, you can have a look at this FAQ.

For security reasons, starting with M³G v1.0, users cannot remove stations anymore from the list of stations for which they maintain the metadata. If you wish to remove a station, send an email to the M³G team including also the motivation why you wish to remove it (e.g., your agency handed over the maintenance of the station metadata to another agency).

1. Update the site log (follow the quick-start guide 5. Edit the site log of an existing station) by entering for the antenna OR the receiver the date of removal of the equipment (Date Removed) in the most recent (i.e. last) section.
2. Save and submit the site log. By doing so, your station will be automatically labelled as (I)nactive.

If you are sure the station will not become active anymore, have a look at this FAQ.

Stations whose metadata are integrated in M³G can belong to GNSS networks and/or GNSS project.

• International networks and projects:
  M³G is currently the official provider of GNSS station metadata for the
  • EUREF Permanent Network (EPN), managed by the EPN Central Bureau at the Royal Observatory of Belgium
  • EPOS-GNSS station network, managed by the Royal Observatory of Belgium
  • EPN densification project, managed by the Satellite Geodetic Observatory, Lechner Nonprofit KFT.
  In addition, M³G also provides information on other GNSS networks to which a station contributes or projects in which the station data are used.
  This is the case for the following external international networks:
  • International GNSS Service (IGS) network, managed by the IGS Central Bureau
  and the following projects:
  • EUMETNET EIG GNSS water vapour programme (E-GVAP), managed by the Danish Meteorological Institute
• Local/national networks:
  These are GNSS networks whose stations belong all to the same agency or which are national GNSS networks
• Virtual networks:
  These are GNSS networks all serving the same goal e.g. VOLC as VOLC regroups the EPOS stations monitoring volcanoes.

Local or national GNSS networks are the only kind of networks that can be set up in M³G by a registered agency.
International GNSS network, projects, and >virtual networks can only be setup by the M³G administrator.

A Station Metadata Maintainer can define local or national networks in M³G, clicking on Edit Metadata (under NETWORKS METADATA) in the agency-specific tab (top right in the website menu bar), available after login.
When defining a new network, the following information is mandatory:

• network abbreviation (must be unique throughout M³G)
• network name
• name of the agency that is responsible for including stations in the network (with a primary and secondary contact). The agency name is selected from a list of agencies that the user has already set up in M³G. This can be your own agency or another agency that has been defined as an associated third-party agency.

Optionally, one can also provide:

• the >DOI associated with the network

Once the networks are defined, a Station Metadata Maintainer can associate each of its stations with one (or more) local/national networks. For this purpose, one can select among all networks defined by M³G users.

All M³G >Station Metadata Maintainers can propose stations to any local/national/virtual network as follows:

1. Login to M³G
(see FAQ)
2. Go to the agency-specific menu (top right in the website menu bar) and click on Propose Station(s) to Network(s)
3. Follow the on-line help at the bottom left of the page (if not visible, click on the )

Upon doing so, M³G will invite the local/national/virtual network manager by email to accept or decline the inclusion of the station in their network.

An M³G registered agency cannot propose a station to any of these networks. M³G will automatically associate stations to these networks based on the information provided by their network managers.
To propose a station to the

• EPN network: follow the Procedure for becoming an EPN station available from http://epncb.oma.be/_documentation/guidelines/procedure_becoming_station.pdf. The EPN Central Bureau will manage the status of your EPN station ("proposed to" (P) or "included in" (I) or "former" (F)) in M³G.
• EPOS network: follow the Procedure for including GNSS stations in EPOS available from https://gnss-metadata.eu/Guidelines/EPOS-GNSS_Procedure_for_EPOS_Stations.pdf. The M³G-Bureau will manage the status of your EPOS station (proposed/included/former) in M³G.

A M³G registered agency cannot propose a station to any of M³G’s projects. M³G will automatically associate stations to a project based on the information provided by the project managers:

• EPN densification project is managed by the Satellite Geodetic Observatory, Lechner Nonprofit KFT (contact details here).
• E-GVAP project is managed by Danish Meteorological Institute (contact details here).

Check out the Guidelines for EPOS-GNSS Stations, Data Suppliers, and Operational Centres, These guidelines are inspired by IGS and EUREF, but the requirements are less strict, to be as inclusive as possible.

A detailed step-by-step guide is available in the Procedure for Including GNSS Stations in EPOS. In case of EPN stations, have a look at Procedure for EPN stations Finally, have a look at the FAQ in this section.

The letter should be signed by the Data Supplier aka the Station Owner which is the agency that has the legal rights to distribute the data and decide whether to decommission a station. This means that the Data Supplier does not necessarily have an account on M³G. Only the Station Metadata Maintainer which by definition maintains the station metadata in M³G needs to have a M³G account. The Data Supplier is responsible for the data flow to EPOS.

The Station Metadata Maintainer indicated in the EPOS Data Supplier Letter, by definition, maintains the station metadata in M³G.

EPOS uses the international RINEX 3 station naming convention: a GNSS station is identified via the 9-char ID: 4-char station ID + 00 + 3-char ISO country code e.g., BRUX+00+BEL = BRUX00BEL
Be aware that the 9-char code of your station will be used for future reference (data and documentation).

1. Login into M³G and go to Edit My Agency Information in the agency-specific tab (top right in the website menu bar)
2. Click on the Edit button below the contact you are interested in
3. Change the phone number and click on Save

Note that the site logs of all stations listed under Used in will be updated automatically.

As in M³G contacts are identified by the e-mail address, you will need to:

1. create a new contact by going to Edit My Agency Information (or Edit Third-party Agencies Information) in the agency-specific tab (top right in the website menu bar) and clicking on in the upper right corner. Insert the contact name whose email you want to change, type the new email address and click on Save.
2. use the contact with the new email address
3. delete the contact with the old email address by going again to Edit My Agency Information (or Edit Third-party Agencies Information) in the agency-specific tab (top right in the menu bar) and by clicking on Delete below the section corresponding to the old contact. If the delete button is not active, it means that the contact with the old email address is still used in the site logs/networks/etc listed in the line USED IN (above the Delete button).

1. Login to M³G
(see FAQ)
2. Go to the agency-specific menu (top right in the website menu bar) and click on Edit only Contacts in Site Log(s)
3. Follow the on-line help at the bottom left of the page (if not visible, click on the )

1. Login to M³G
(see FAQ)
2. Go to the agency-specific menu (top right in the website menu bar) and click on Edit only Data License & Embargo Period
3. Follow the on-line help at the bottom left of the page (if not visible, click on the )

1. Edit, validate and submit your site log changes in M³G.
2. After submission, you will be redirected to the Edit all Metadata table:
   • click on the station name under the column 9-CHAR ID and a modal window will appear
   • click on the (next to the station name, top left) to export to the IGS format and save it to your local disk
3. Go to the IGS Site Log Manager and upload the site log that you just saved.

1. Follow the steps in the quickstart guide 5. Edit the site log of an existing station
2. Once you get redirected to the site log editor, go to the specific section, make your changes and save

Note that you can always upload the updated site log from your local disk (have a look at the quickstart guide 6. Upload a site log of an existing station

1. After login, go to the agency-specific tab (top right in the menu bar), click on Edit all Metadata. You will be redirected to a stations overview table.
2. Click on one of the icons in the column UPDATE SITE LOG for the station that you are considering and follow the instructions.

You can also have a look at the quickstart guide 6. Upload a site log of an existing station.

In order to comply with GDPR, M³G is linking all the agency/contact information in the site logs with the information entered in Edit My Agency Information and Edit Third-party Agencies Information in the agency-specific tab (top right in the menu bar). Therefore, check the following information in the site log editor from under Owner/Contact:

• Prepared by: you can only select one of the public non-personal contacts of your agency entered through Edit My Agency Information
• Responsible Agency: you can select your own agency or one of the third-party agencies.For EPOS stations, only the Data Supplier appearing in the EPOS Data Supplier letter can be selected.
• On-Site, Point of Contact Agency: you can select your own agency or one of the third-party agencies.
• the Primary and Secondary Contacts can be selected from the predefined contact list of the selected agency. As Primary Contact you can only choose among a list of public non-personal contacts. If the contact is not in the list, click on the last item in the dropdown menu Add contact to profile and complete the information of the new contact.

You can download the content of the site logs via the M³G file server from:

• https://gnss-metadata.eu/data/station/log - IGS site log format
• https://gnss-metadata.eu/data/station/xml - GeodesyML format
• https://gnss-metadata.eu/data/station/general - SINEX header including historical station information (generated from site logs).

M³G discourages the use of personal data, but requires contact information for the agencies that are registered or set up in M³G. This information is entered in M³G by the registered agencies themselves through the Edit My Agency Information and Edit Third-party Agencies Information submenus, in the agency-specific tab (top right in the website menu bar). The agencies must use at least one public non-personal contact (e.g. email aliases pointing to a team). The mandatory information is the agency name (and abbreviation), address, name of the team and the corresponding public non-personal email.

Please check ROB's general privacy policy and the specific M³G privacy policy.
M³G personal data management complies with the EU General Data Protection Regulation (GDPR). You are encouraged to use non-personal contacts ((e.g. email aliases pointing to a team). However, if you decide to use a personal contacts, please note that the person in question will be asked by email if he/she agrees that his/her contact information is made publicly available without restrictions. If the person declines, then the corresponding contact information will not be exported (in e.g. site logs) and will be replaced by the public non-personal contact information of the agency.

1. Go to Edit My Agency Information in the agency-specific tab (top right in the menu bar)
2. Delete the contact clicking on Delete button.

If the delete button is not active, it means that the contact is still used in a site log, a network, etc. listed in the line USED IN.
If the contact is used in a site log, you have to first update the site log by inserting another contact. Once the contact that you wish to remove is not used anywhere else in M³G, the delete button will become active.

Your personal contact information has been entered in M³G. M³G asks you if you agree to make this information publicly available without restrictions (check our privacy policy).
M³G will be sending you this kind of emails as long as you do not reply. If you decline the request to make your personal data publicly available, your personal contact data will be removed from all the metadata published M³G and will be replaced with the public non-personal contact of your agency.

If your agency is registered in M³G:

1. go to the Edit My Agency Information in the agency-specific tab (top right in the menu bar)
2. look for your name in the list of contacts, click on Send GDPR e-mail button corresponding to your name and you will get a new email request from M³G allowing you to change your decision.

If your agency is not registered in M³G and, for example, your name has been provided as e.g. a contact for a third-party agency:

1. ask the appropriate registered agency to send you a new email. They can do this by logging into M³G, going to the Third-party Agencies menu, and clicking on Send GDPR e-mail button corresponding to your name.
2. You will get a new email request from M³G allowing you to change your decision.

In the case of the Primary contact, which can only be selected among the public non-personal contacts, you will not see it in the exported site log if the email address of the contact has not been confirmed.
The Secondary contact gets stripped from the site log only if it contains personal contact information (subject to EU GDPR) and M³G was not granted permission to make this information publicly available (the person did not respond positively to the GDPR email from M³G).

Yes, M³G can manage this. Proceed as follows:

• Login into M³G
• Go to Edit Third-party Agencies Information in in the agency-specific menu (top right of the menu bar)
• Set up a new agency, by clicking on (top right)
• If your station is co-owned
• by 2 agencies X & Y (abbreviations of the agency names), then use X & Y for the Agency ID and Abbreviation (Please note: "Agency Abbreviation" can be up to 10 characters.)
• by several agencies, then use e.g. the Consortium Name to complete the Agency ID and Abbreviation (Please note: "Agency Abbreviation" can be up to 10 characters.)
• Fill in the address, as you would like it to appear in the site logs.
• Insert the contacts that you want to use in the site logs.
• Click on Save

To create a new station, check how to set up/add a new station

To upload the site log, check how to upload a site log of an existing station

Before validating the site log, ensure that the Responsible Agency section in the site log properly indicates X & Y or the Consortium.