One way that planets are categorized as they are charted is by habitation class. There are multiple levels to this classification, and they start with a biodiversity level. If the planet is observed to habitate no life whatsoever, it is given the initial habitation classification code (HCC) of BD0. If it is deemed that the conditions of the planet would make any habitation of life on the planet fundamentally impossible, the planet is marked as BDX. If the planet is home to incredibly sparse or desparate ecosystems, it is labeled with BD1. The BD scale continues to measure biodiversity up unto a fifth level, which would mean an incredibly diverse and thriving planet, full of incredibly varied ecosystems. Any planet which has been documented as having a BD score equal or lower to BD2 is functionally labeled as a dead planet. If the planet was known to have a higher BD score in the past, the value "AI" (Archeological Interest) is appended to its ultimate HCC. If the planet is not a dead planet, what's known as a "Presence Index Level" or simply "P-level" is then appended to its HCC. P-Level ranks the highest level of sapience present within the planet's species. P-levels are: N - N/A M - Microbial life V - Vegetative/plant or fungal life N - Nonsentient animalistic life E - Sentient animalistic life S - Sapient tribal or primitive life S+ - Civilizational sapient life SP - Interplanetary sapient life P-level is appended to the HCC as PN, PM, PV, PN, PE, et cetera. Finally, appended to a planets HCC is its hostility level, which measures how hostile the planet and its denizens typically are to travelers they aren't familiar with. Hostility level is appended to the HCC as HN, HA, HE, HX, HXX, et cetera. N - N/A A - Accomodating/welcoming to travelers E - Neutral or afraid of travelers X - Hostile animals, no sapient danger XX - Hostile sapient danger XXX - Extreme hostile sapient danger GI - This planet's sapient governance does not allow any travelers, and there may be legal consequences for landing here.