The full, uncommented, version of this file is in the demodata directory in file dep.ngh.
The format is:
Line 1: NREC - the number of nodes in the file - integer
Line 2: MAXNGH - maximum number of non-zero neighbours in this grid
Line 3: RANGES - four values, which are XHIGH, YHIGH, XLOW, YLOW - floating point numbers
Lines 4..4+NREC-1: NREC lines containing information about each node (NODENO, X, Y, depth, computational code, and a list of its neighbouring node numbers)