Variance decomposition: oo_.gamma{nar+2}

Hello!

After running simulation, I want to see results of Variance decomposition.
Dynare mannual suggest the following command

oo_.gamma{nar+2}

What is nar mean?

When typing it in command window, it gives following error:

Undefined function or variable ‘nar’.

Can anybody help me?
Thanks a lot!

nar is stored in