Planetological classification system (Derived from Orion's Arm Universe Project)
Surface composition types:
-Ferridian: Iron
-Selenian: Rocky and silicate
-Carbidian: Carbonaceous
-Glacian: Solid of sea fluid types such as ices, sulfurs, quartzes
-Jovian: Gaseous, primarily made of hydrogen and helium

Surface types (for non-Jovian planets):
-Terramare: Planets have continents and oceans on its surface.
-Cytherean: Planets are completely cloaked by clouds and supercritical fluids, resembling Venus.
-Europan (for Glacian planets): Planets have subsurface oceans.
-Martian: Desert planets with 0% sea level, surface is covered by sands and oxides.
-Oceanic: Ocean planets with 100% sea level.
-Sparsian: Sparse atmosphere existing with a pressure above 0.1 nanobar, falling in the atmospheric density range between that of Luna and Mars.
-Airless: Planets lack atmospheres.

Sea level (for Terramare planets):
-Oceanic: 100%
-Pelagic: 90-100%
-Marine: 60-90%
-Estuarine: 40-60%
-Lacustrine: 10-40%
-Arid: 0-10%
-Desert: 0%

Cytherean subtypes:
-Greenhouse: Carbon dioxide clouds.
-Misty: Water clouds.
-Titanian: Orange clouds of Titan-like planets.
-Azotic: Nitrogen clouds.
-Hydronian: Clouds of hydrogen and helium. As Chthonian planets, it almost lost envelope of hydrogen and helium, resembles Frigidian version of Venus.

Other planet types:
-Chthonian (for non-Jovian planets): Planets lost envelope of hydrogen and helium.
-Genesian: Artificial planets are constructed.
-Permatholian (for Jovian planets): Below temperature zone, Jovian planets have permanent non-cloud (haze or smoke, soot, dust, snow, etc.) of aerosol types, and losing temperature, never raining. Permatholian planets have diverse types, except MesoAzurian, PyroAzurian, HyperPyroAzurian. MesoAzurian, PyroAzurian, HyperPyroAzurian will becomes Permatholian CryoAzurian when it ejected.

Sea fluid types (Surface and subglacial):
-Wateric: H2O
-Ammonic: NH3
-Methanic: CH4
-Sulfic: H2S
-Nitric: N2
-Nitroxic: NO2
-Brimstonic: S (molten sulfur)
-Cyanogenic: (CN)2
-Carboxic: CO
-Neonic: Ne
-Helic: He
-Oxygenic: O2
-Hydrogenic: H2
-Carbonylic: Iron carbonyl
-Saltic: NaCl (molten salt)
-Quartzic: SiO2 (molten silica)

Atmospheric composition types:
-Hydrogean: Hydrogen-dominated atmosphere
-Helian: Helium-dominated atmospheres
-Hydridian: Atmospheres dominated by simple hydrides (CH4, NH3, H2O, HF)
-Diatomian: Atmospheres dominated by diatomic non-metals (N2, O2, F2)
-Chemonian: Atmospheres of other non-metal compounds (CO, CO2, SO2, NO2, HNO3, CS2, HCN)
-Metalloidian: Metal and metalloid compound atmosphere (SiO2, MgO, FeO, NaCl, Na, Fe)
-Edelian: Atmospheres dominated by other noble gases

Evolutionary stages of life:
-Protobiotic: Worlds undergoing abiogenesis, rich in prebiotic molecules like protocells and other life-like organisms. Usually only a brief phase, but may become greatly extended by various planetary factors.
-Microbiotic: Most common type of biotic world. These worlds host microbial life, often of low complexity.
-Mesobiotic: Worlds with simple colonial, multicellular, and/or megacellular organisms.
-Macrobiotic: Worlds hosting a well developed ecosystem of macroscopic multicellular, colonial, and/or megacellular organisms.
-Neobiotic: Worlds that have had life introduced from another world or heavily modified by artificial means.
-Postbiotic: Worlds that had once hosted life which has since completely died out.

Aerosol composition types of clouds/hazes over thick atmosphere of hydrogen and helium (for Jovian planets):
-Letter - Demonymic name (Temperature zone for non-Permatholian planets, where it can be found commonly; hex color): Chemical composition
-A - CryoAzurian (Clarified, 5-90 K; #c4eeff): CH4.
-B - Frigidian (Cloud, 5-20 K; #f5f6ff): None. Clear and pristine, devoid of chemistry.
-C - Neonean (Cloud, 15-35 K; #ffebeb): Ne.
-D - Lilacean (Cloud, 35-60 K; #fdf5ff): N2, CO, O2.
-E - Methanean (Cloud, 55-90 K; #c4f8ff): CH4, C2H6, Ar
-F - MesoAzurian (Clarified, 90-550 K; #41d9d9): Organic compounds and sulfur
-G - Tholinian (Haze, 60-550 K; #ffad66): Tholin, but nitrogen and methane, like atmosphere of Titan.
-H - Sulfurian (Cloud, 80-200 K; #fff2ba): H2S, NH3, (NH4)HS, HCl, SO2.
-I - Ammonian (Cloud, 75-190 K; #ffe8bf): NH3, NH4HS, (NH4)2S, H2O, CO2.
-J - Waterian (Cloud, 170-360 K; #ffffff): H2O.
-K - Acidian (Cloud, 200-570 K; #fff8d4): H2SO4, H3PO4, NH4H4PO4, H2O, NH4Cl.
-L - PyroAzurian (Clarified, 550-1300 K; #0077a6): CH4.
-M - Thiosulfian (Haze, 400-1000 K; #cccc7a): Sulfur and organosulfur compounds.
-N - Siliconelian (Haze, 550-1000 K; #7d9999): Siloxane, fluorosiloxane, and other organosilicon compounds.
-O - Chloridian (Cloud, 620-900 K; #edfae1): CsCl, RbCl, KCl, ZnS.
-P - Alkalian (Cloud, 800-1150 K; #59593e): LiF, Li2S, Na2S, NaCl.
-Q - Manganean (Cloud, 1100-1500 K; #4a766e, #d07d92): Cr, MnO, MnS.
-R - HyperPyroAzurian (Clarified, >1300 K; #0047ab): CH4.
-S - Silicatian (Cloud, 1200-1900 K; #667d80, #688066): Fe, FeO, MgO, SiO2.
-T - Rutilian (Haze, 1400-2000 K; #0d0904): TiO, TiO2, VO2.
-U - Corundian (Cloud, 1700-2350 K; #225ab5, #ccc9b8): Al2O3, CaO, calcium aluminates, perovskite.
-V - Carbidian (Cloud, 2000-2900 K; #1a1310): TiC, CaC2, VC, VC2, TiN, VN, SiC.
-W - Fuliginian (Haze, 2600-3400 K; #030004): C.