Perhaps a tangent, but until now, I've only seen or used "codec" in the audio/video sense. While somehow awkward, it seems this would also be correct, since it also compresses and decompresses. Video codec but archive format.
Sometimes you see a word used a new way and wonder if you've just been wrong all these years.
The defining factor isn't compression/decompression, it's just encoding.
You'll see codec used in things like text encoding.