Can parse_oid_indexes() parse fixed-length string indexes?

I don't see in the table registration any information about the indexes'
length (in case of fixed-length string)
 
And there is also no information about the length in the parameters of
parse_oid_indexes()
-------------------------------------------------------------
int parse_oid_indexes(  oid * oidIndex, size_t oidLen,
                        netsnmp_variable_list * data)
------------------------------------------------------------
 
So how can it work properly?
 
thanks,
Erez Makavy