MARS - A Software Dedicated to Advanced Concrete Modeling

The command write NodeDataFile does not export the nodal coordinates.
The list of node IDs by itself is almost useless.
It is for sure not what someone would expect from a "NodeDataFile"

I recommend exporting the coordinates of the selected nodes together with the node ids.
This would increase the value of this feature significantly

I tried attached input, it does output the coordinates. Can you post your input file?

I tried another example where I also get the coordinates in the first case (AllNodes.mrs) but not in the second (SelNodes.mrs).
Obviously, you get the nodal coordinates only for the original nodelist while the result of the MakeNodeList contains just the pointers.

I suggest adding the coordinates of the linked nodes anyway to avoid the need of writing two nodelists and looking up the coordinates afterwards manually ...
I also suggest explaining this in the manual ("ReadNodes xxx" vs "Link nodes list1 zzz").

BTW: the second output (SelNodes.mrs) contains a single curly bracket - that's probably a bug.

In the first case:
// Node data for PRTC

LengthUnits m
Particles
ReadNodes 1514
// i crx cry crz rad
1 -1.000000014901e-01 -1.000000014901e-01 -3.000000119209e-01 0.000000000000e+00
2 1.000000014901e-01 -1.000000014901e-01 -3.000000119209e-01 0.000000000000e+00

In the second case:

Node data for SelNode
LengthUnits m
Link PRTC nodes 2
1518 1980
}
EOF

Since version 2016.8.12, the command will always write coordinates, even it's a linked node list.

Thank you!