The web is a great way to get information about subjects like ham radio that you might never find if you had to rely on books. Unfortunately it's also a good way to get wrong or obsolete information. For example, people looking for advice on how to make their first contacts via amateur satellites will find many articles that explain in great detail how to work through satellites that have long been defunct - even on the Amsat website!
There are numerous websites that explain about SSIDs used for APRS. (An SSID is the numeric suffix to the call, for example G4ILO-7, which is used to distinguish an operator's APRS devices and also to give an idea of what type of device it is.) They are all wrong! Bob Bruninga, WB4APR, the inventor and ultimate authority on APRS, released an updated set of recommendations on 9 June this year to provide more flexibility for current usage.
The new recommendations are:
-0 Your primary station, usually fixed and message capable.
-1 Additional station, digi, mobile, weather station etc.
-2 Additional station, digi, mobile, weather station etc.
-3 Additional station, digi, mobile, weather station etc.
-4 Additional station, digi, mobile, weather station etc.
-5 Network sources (smartphones etc.)
-6 Special activity, e.g. satellite operations, camping, 50MHz etc.
-7 Handheld radios and other human portables.
-8 Boats, RVs or second mobile.
-9 Primary mobile.
-10 Internet gateways, Echolink, Winlink, AVRS, APRN, etc.
-11 Balloons, aircraft, spacecraft, etc.
-12 APRStt, DTMF, RFID devices, trackers etc.
-13 Weather stations.
-14 Truckers or other full time drivers.
-15 Additional station, digi, mobile, weather station etc.
These are recommendations and not set in stone, but they are intended to help people know what type of device or application is being used, particularly in situations where someone doesn't have a graphical map display and can't see an icon.
Due to these recommendations I am now using G4ILO-5 for my Windows smartphone running APRSISCE. My VX-8GR remains G4ILO-7. My main 2m station is G4ILO-0 or just plain G4ILO, and my HF station is G4ILO-1.
Of course, this page could also become out of date in the future so I am including this link back to the original document in case Bob should make any further changes.