can someone tell me what the following code do

[ronlahav]

<SCRIPT LANGUAGE=vbscript runat=server>
sub Application_OnStart
dim arrOnLine(50,3) Application("OnLineUsers") = arrOnLine
end sub
</SCRIPT>

<SCRIPT LANGUAGE=vbscript runat=server>
sub Application_OnEnd
' Remove Session Users
Application.Lock
arrOnLine = Application("OnLineUsers")
for i=0 to UBOUND(arrOnLine,2) if arrOnLine(0,i) = Session.SessionID then
arrOnLine(0,i) = ""
arrOnLine(1,i) = ""
exit for
end if
next
Application("OnLineUsers") = arrOnLine
Application.UnLock
end sub
</SCRIPT>

what is the structure of the array????? its location is in global .asa
thanks