about GN card in GFGEN

[WildCat 0]

I meet some trouble .

the following are three rows of my GFGEN file(.geo)

GNN 1 298774.7226 4871503.9420 0.0000

GNN 3 298589.9983 4871545.3755 0.0000

GNN 5 298645.0820 4871599.8810 0.0000

we can see that only node #1,3,5 was displayed.

and in GFGEN help doc ,it is said in GN card "c0l3=N " means Values to be assigned to node J only (insert all ISI=b cards before first N card)

I can't understand the sentence.

Why only corner codes has x-y-coordinate while midside nodes do not?

does sms caculate the x,y-coordinate of midside nodes when running the model?

If I want to get allow the geo data of all the nodes ,what shall I do ?

In addition,each concentration was listed of each node in RMA2 or RMA4 solution file .

THANK YOU!