What do the subscripts mean in $N_{t,n,\sigma,L}$?

A neural network can apparently be denoted as $$N_{t,n,\sigma,L}$$. What do these subscripts $$t, n, \sigma$$ and $$L$$ mean? Could you link me to a paper, article or webpage with an explanation for this?

• Does "size $n$" mean that the network has $n$ input nodes? – J. Doe Nov 13 '19 at 9:08