Grade 2 planet

From Tardis Wiki, the free Doctor Who reference

Grade 2 planets were planets deemed advanced enough to be allowed to be opened to the importation of alien technology. As such, the Magellanic Mining Conglomerate were allowed to mine on such worlds. In contrast, the grade 3 planet Ribos, which was projected as being many thousands of years away from grade 2 status, was off-limits to the Conglomerate since the inhabitants were unaware of other life forms. (TV: The Ribos Operation)