Welcome to the M3G web site. M3G stands for “Metadata Management and distribution system for Multiple GNSS Networks”. The system allows to upload, validate, and distribute GNSS station metadata (e.g. site logs) and has been developed primary to serve the EPOS, EPN, and EPN densification GNSS networks.

Using M3G

M3G collects more than only the IGS-style site log files. It allows to collect also information about local networks, DOI, provided data, etc... To edit station metadata, you must first login. All agencies maintaining EPN or EPN densification stations metadata (the so-called Operational Centers) have received their login by email. Agencies maintaining metadata of EPOS stations will be sent a login as soon as we receive the completed and signed EPOS-GNSS supplier letter from the Data Supplier.

Visit the Guidelines section for the responsibilities of Data Supplier and Operational Centre.

Site log update

  • Site log updates for stations labelled as "EPN" or "EPN densification" in M3G will automatically flow to the EPN Central Bureau.
  • Site log updates for stations labelled as "EPOS" will automatically flow to the EPOS GNSS Data Gateway.


  • M3G is still under development, but offers already a lot of functions.