Found this in a Samsung FAQ, looks like either an old way to name files, or specific to whatever player Samsung uses:
Video Type________________________________________________ Code
================================================ =================
2D video........................................................................................ "2dp"
3D top bottom video................................................................... "3dpv"
3D left right video........................................................................ "3dph"
Monoscopic 180........................................................................... "180x180"
Monoscopic 180 16:9.................................................................. "180x101"
Left right stereoscopic 180 16:9................................................ "180x101_3dh"
Monoscopic 360 equirectangular projection........................... "mono360"
Top bottom stereoscopic 360 equirectangular projection.... "3dv" or "tb"
Left right stereoscopic 360 equirectangular projection......... "3dh" or "lr"
Monoscopic 360 cube projection............................................... "cubemap "
Top bottom stereoscopic 360 cube projection....................... "cubemap_tb"
Left right stereoscopic 360 cube projection............................ "cubemap_lr"
Monoscopic 360 octahedron projection.................................. "octahedron"
Monoscopic 360 icosahedron projection................................. "icosahedron"
Top bottom stereoscopic 3D 180.............................................. "180x180_3dv"
Left right stereoscopic 3D 180................................................... "180x180_3dh"
Left right stereo 3D 180 squished............................................. "180x180_squished_3dh"
Top bottom stereoscopic 3D 180x160...................................... "180x160_3dv"
Two monoscopic 180 hemispheres........................................... "180hemispheres" or "180-hemispheres"
Top bottom 3D cylinder 2.25:1................................................... "cylinder_slice_2x25_3dv"
Top bottom 3D cylinder 16:9...................................................... "cylinder_slice_16x9_3dv"
Top bottom 3D 360 no bottom................................................... "sib3d"
180 planetarium full dome......................................................... "planetarium" or "fulldome"
V360 camera................................................................................. "v360"
RTXP 360 cylindrical..................................................................... "rtxp"