H = message "hash"
T = local station time
A = a's station time, stamped in messages. synced to local time
B = b's station time, stamped in messages. +4sec relative to local time

H=0 T=0 A=0 <a> hi
--- turn local station off for updates
H=1 T=1 B=5 <b> sup
H=2 T=2 A=2 <a> not much
--- turn local station on
H=3 T=3 B=7 <b> cool
--- getdata(1) called
H=4 T=4 A=4 <a> yep
--- getdata(2) called
...
--- getdata(1) returns
--- "<b> sup" displayed, stamp is 5
--- stamp of most recent message displayed was 4
??