Tables with multiple index

[ABY PHILIP]

Pardon me if this sounds too naive. But some doubts regarding SNMP agent
behavious if it is to implement table with multiple variables.

1. Consider there are 2 index (both INTEGER) for a table. Both are the
variables in the same table. Also the table is sparse. Not every combination
of the index values may not exist.

e.g. Say index1 and index2 exist as - 

1.2 // exists
1.3 // does not exist
2.2 // does not exist
2.3 // exist

My question is how a GET on index1 / index2 variable should behave. Should
it list all the instances?

2. If the instance values of index2 depends on the value of index1 then how
can the MIB be defined?

e.g. index1,index2,var3 are variables
1.2.1 exists but 1.3.1 does not

thanks for your time

best regards
Aby Philip