V$STATNAME
displays decoded statistic names for the statistics shown in the V$SESSTAT
and V$SYSSTAT
tables.
On some platforms, the NAME
and CLASS
columns contain additional operating systemspecific statistics.
Column  Datatype  Description 

STATISTIC# 
NUMBER 
Statistic number
Note: Statistics numbers are not guaranteed to remain constant from one release to another. Therefore, you should rely on the statistics name rather than its number in your applications. 
NAME 
VARCHAR2(64) 
Statistic name 
CLASS 
NUMBER 
A number representing one or more statistics classes. The following class numbers are additive:

STAT_ID 
NUMBER 
Identifier of the statistic 
See Also:
Appendix E, "Statistics Descriptions" for a description of each statistic
Your operating systemspecific Oracle documentation