Timerover51
SOC-14 5K
And also to the biggest problem with all the canonical definitions of population. It's not described if only inhabitants (what we'd call today citizens, those calling it home) are counted or transient people (those who may be there even for some years, but who call home elswhere) is too.
I go with the population number of the planet being the average population, permanent and transient, except for Asteroid Belts, where the population is that of the Belt as a whole.
On very low population planets with a high Tech level, I assume that the population is there to exploit some valuable resource, and the the Tech Level refers to what may, if available, be purchased there. Maintenance is a different story.
To produce the full spectrum of items at a given Tech Level, I figure that for Tech Level 4, you need a population in the millions, and for Tech Level 5, in the tens of millions. For Tech Level 6 and higher, a population in the hundreds of millions, assuming a unified planetary government. With lower populations, not everything can be made and/or maintained locally, so imports are necessary.