I stand corrected. You are correct, they could use a field or combination of fields of the planet data to generate a unique seed value.

With some experimentation, it should be possible to determine if planet number or the location of its star have an effect. If you move the star system it's in but the terrain stays the same, the seed is not based on the position. If it does change, we can assume it does.

According to the data in SFFiles.zip provided in the other topic, Starflight I apparently did have random seeds for terrain, lifeforms, and ruins, so it is reasonable to suspect that Starflight II did also.

However, jokedst is correct. Unless we can find another table of planetary data and locate the seeds (and demonstrate they are the seeds by changing them), there is no way to tell for sure exactly what the programmers did.