What is sys_op_opnsize, exactly?

OSEE 10.2.0.2 on Solaris 8

When tracing dbms_stats, I came across this system call. Anyone know what its function is, and why dbms_stats collects the sum of this function for a column? Character datatypes seems to always = length (ie, sys_op_opnsize(column) = length(column)). Date datatypes seem to be 7
(length 17). The number datatypes really confuse me, as sys_op_opnsize is
not equal to length or the number of bytes used to store the value
(sys_op_opnsize(1) = 2).

I am probably missing something obvious, but this caught my curiosity.

Thanks,

-- 
Charles Schultz

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