spid       :oratop's server SPID connected to instance,
   SID        :instance name (First 4 letters), 
   clock      :Time of current stats collected (hh24:mi:ss)
   time       :uptime since this instance startup,
   ins        :Total number of active database instance(s),
   MT         :database total memory (sum Memory_Target),
   ses        :Total user's sessions,
   usr        :Total distinct database foreground (F/G) users,
   %DB      :%database Active, 0 0ndicate idle db

Section 2- Cluster-wide "Top 5 instances activity" ordered by Wait Time 
   ID         :instance id,
   %HC        :Host CPU Utilization, %(busy/busy+idle),
   HLD        :Current Host Load,
   MBPS       :throughput, 'I/O Megabytes per Second',
   %FR        :Shared Pool Free %,
   PGAU       :total PGA inuse,
   IORL       :Avg Synchronous Single-Block Read Latency,
   PQS        :PQ Slave Session Count,
   ASC        :Active Sessions on CPU,
   ASI        :Active Sessions waiting on user i/o,
   ASW        :Active Sessions waiting/sleeping,
   AST        :Total Active Sessions,
   ASB        :Active Sessions blocked,
   AAS        :Average Active Sessions,
   CTPS       :(CPS) User Calls Per Sec, OR,                (TPS) User Transactions Per Sec (appears in RED),
   SSRT       :SQl service Response time,
   DBC        :database cpu time ratio,
   DBW        :database wait time ratio.

Section 3- Cluster-wide "Top 5 Timed Events" ordered by Wait Time 
   EVENT      :database wait event,
   WAITS      :cluster average Total waits,
   TIME(s)    :cluster average Total wait time in seconds),
   AVG_MS     ::cluster Average wait time in milliseconds,
   PCT        :Percent of wait time,
   WAIT_CLASS :Name of the wait class corresponding to the event.

Section 4- Session/process none-idle ordered by Wait Time desc.
   ID         :instance id,
   SID        :session id,
   SPID       :server process os pid,
   USR        :user name (abbreviated),
   PROG       :program name (abbreviated),
   PGA        :process pga used,
   OPN        :OPERATION name, e.g. SELECT,
   SQLID      :SQL identifier if no blocker, else,
   /BLOCKR    :final blocking instance:session:ospid,
   E/T        :Elapsed Time since the session has become active. Units: (s)econds, (M)inutes, (h)our, (d)ay.
   STATUS     :ACTIVE | INACTIVE | KILLED | CACHED | SNIPED,
   STE        :Process STATE: ON CPU or USR I/O or WAITING,
   WAIT_EVENT :process wait event name,
   W/T        :Wait Time. Units: (u)-micro second, (m)illi second, (s)econds, (M)inutes, (h)our, (d)ay.