Data are available in the RINEX (Receiver-INdependent data EXchange) format, version 2.10 or more recent (ftp://igscb.jpl.nasa.gov/igscb/data/format/rinex210.txt), with Hatanaka compaction (ftp://terras.gsi.go.jp/software/RNXCMP_4.0.4/) and UNIX compression applied. We propose to comply with the directory structure used by the IGS (International GNSS Service, http://www.igs.org) data centres: daily session for each site are stored in separate observation files and grouped in day directories; the day directories are grouped in year directories.