A message at login might look like this:
keyval:{
"speed":"mph",
"homeLatLon":"-1.12345,50.12345,30",
"map":"google"
"timezone":"auto"
}
To set one or more values:
keyval:{
"speed":"mph",
"timezone":"auto"
}
To delete, just send a blank value:
keyval:{
"map":""
}