Comparing current worldwide SBAS coverage – based on WAAS, EGNOS and MSAS – to the situation envisaged for 2020–25: near-global coverage based on WAAS, EGNOS, MAAS, SDCM and GAGAN, with an expanded network of stations in the southern hemisphere, all based on a common dual-frequency/dual satnav standard being finalised by the SBAS Interoperability Working Group.