hi seniors,

can you explain the founction of Cnode which is used in the restrains?

Place your cursor on the CNODE box and press F1.
F1 is your friend

As a learner you need to get more familiar with the guides within the software. Go to help you will reach them instantly if you do not have printed version.
There are some sample problems in the guide books that very handy to understand the magic of CNODE.

Ibrahim Demir