Where does the DSC file name prefix come from?
Without having a real problem with this, why did Nikon (maybe others too?) chose this file name prefix?
Additionally, I noticed that Nikon uses "CSC" for photos converted from RAW in-camera after the fact (using the menu-based interface for doing so).
@mattdm - in my experience every image you make some in-camera adjustment to, not just from raw, is saved as a copy with "CSC" prefix.
Yes, but what does "Digital Still Camera" mean?
CIPA (the Camera & Imaging Products Association) has long established DSC as meaning Digital Still Camera. This prefix is not mandated by the DCF (Digital Camera Filesystem) standard but was adopted uniformly by Nikon and Fuji which named their files starting with DSC_, DSCN, or DSCF. Other manufactures went with PICT, PIC or P which presumable all stand for Picture. Although plenty of cameras also save videos with the same convention.
You will notice that DCF requires files in AdobeRBG color-space to start with an underscore, in which case DSC is often all that is left and you get _DSCxxxx.yyy uniformly for Nikon and Fuji.
As ahockley pointed-out, Sony coincidentally uses the DSC prefix for fixed-lens camera names as well.
What is CIPA? A quick googling reveals several uses for that acronym, none of which seem to apply to imaging...