97.20.-w Normal stars (by class): general or individual
- 97.20.Ec Main-sequence: early-type stars (O and B)
- 97.20.Ge Main-sequence: intermediate-type stars (A and F)
- 97.20.Jg Main-sequence: late-type stars (G, K, and M)
- 97.20.Li Giant and subgiant stars
- 97.20.Pm Supergiant stars
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97.20.Rp Faint blue stars (including blue stragglers), white dwarfs, degenerate stars, nuclei of planetary nebulae (for planetary nebulae, see 98.38.Ly or 98.58.Li)
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- 97.20.Tr Population II stars (horizontal branch, metal poor, etc.)
- 97.20.Vs Low luminosity stars, subdwarfs, and brown dwarfs
- 97.20.Wt Population III stars