.nc, .ncc, .tap, and maybe .txt are all G-code files.
All of those are plain text, and they all look something like this, and the name of this particular file is 1001.nc, but it could have a .tap, or .ncc extension and it would be the same.
(1001)
(T1 D=0.25 CR=0 - ZMIN=-0.2 - flat end mill)
(2D Contour1)
N4650 M8
N4655 G0 X3.2075 Y-0.9815
N4660 G1 Z0.2 F8
N4665 Z0.0394
N4670 Z-0.175
N4675 G18 G3 X3.1825 Z-0.2 I-0.025 K0
N4680 G1 X3.1575 F24
N4685 G17 G3 X3.1325 Y-1.0065 I0 J-0.025
N4690 G2 X3.0768 Y-1.1105 I-0.125 J0
N4695 G1 X1.5768 Y-2.1105
N4700 G2 X1.4382 I-0.0693 J0.104
N4705 G1 X-0.0618 Y-1.1105
N4710 G2 Y-0.9025 I0.0693 J0.104
N4715 G1 X1.4382 Y0.0975
N4720 G2 X1.5768 I0.0693 J-0.104
N4725 G1 X3.0768 Y-0.9025
N4730 G2 X3.1325 Y-1.0065 I-0.0693 J-0.104
N4735 G3 X3.1575 Y-1.0315 I0.025 J0
N4740 G1 X3.1825
N4745 G18 G2 X3.2075 Z-0.175 I0 K0.025
N4750 G0 Z0.2
N4755 G17
N4760 M9
N4765 M2