The name is verified by in-game jukebox.
Wolfenstein 3D (DOS)
P.O.W. is played in E1M3, E1M7, E4M3, and E4M7 of Wolfenstein 3D (DOS).
This tune is the 10th IMF file in the AudioT.WL6 file. The IMF's meta tag lists the title as "POW".
Spear of Destiny (DOS)
P.O.W. is played in level 8 of Spear of Destiny (DOS).
This tune is the 10th IMF file in the AudioT.SOD file. It is not included in the demo release of Spear of Destiny.
Wolfenstein 3D (JAG)
The song's internal name is "0POWF".
Voxelstein 3D (W32)
Wolfenstein 3D (WEB)
Wolfenstein 3D (GEN)
This track has the difference that it is based on OPN2 from Genesis from the DOS version..