B0V

Garrison94 lists the B0V dagger as Ups Ori = HD 36512

Lesh68 lists Ups Ori & Tau Sco as B0V standards. 

Abt68 lists HD 46106 as their B0V standard. 

Walborn72 & Walborn90 list Ups Ori as the B0V standard, with Tau Sco
as the B0.2V.

Hiltner69, Garrison77, Garrison79 list Tau Sco as its B0V standard.  

MK43 lists Tau Sco as "B0V" standard and 139 Tau as "B0" standard.

Garrison94 lists Tau Sco as a B0V dagger, but Walborn72 calls it
B0.2V.

Lesh68 classified two stars as B0V: HD 202214 & HD 36512. 

Garcia89 lists 4 B0V MK standards: HD 36512, 149438, 206183, 207538
Skiff08 lists two B0V standards: Hd 36512 (MK73) & HD 149438 (MK78)

Median Mermilliod91 colors among the standards:
<B-V>(B0V) = -0.280
<U-B>(B0V) = -1.0505

# Dagger Standards
HD 36512 = ups Ori = HR 1855
  B0V: Jaschek78(JM53),Jaschek64(all but one),Lesh68(stan),Walborn71,Walborn72,MK73,Abt77(B0Vs),Garcia89,Walborn90,Garrison94,Houk99(Garrison),Russeil07
  B0.5V: Lesh68(stan)
  B3: Cannon
  M91: V=4.618+-0.013, B-V=-0.264+-0.007, U-B=-1.068+-0.008
  =>QBV=> (B-V)o=-0.281, (U-B)o=-1.053, E(B-V)= 0.017, T=29944.

# Good standards
HD 149438 = tau Sco = HR 6165
  B0V: MK43,Lesh68(stan),Jaschek78(JM53),Bertiau58,Jaschek64(all),Garrison67,Hiltner69(stan),MK73,Garrison77(stan),MK78,Garrison79(stan),Houk82,Keenan85,Garcia89,Garrison96
  B0: Cannon
  B0.2V: Walborn71,Walborn90
  M91: V=2.825+-0.009, B-V=-0.252+-0.007, U-B=-1.023+-0.013
  =>QBV=> (B-V)o=-0.270, (U-B)o=-1.010, E(B-V)= 0.018, T=28066.
  Basically was unanimously B0V until Walborn called it B0.2V

# Secondary Standards?
HD 206183 = Cl Trumpler 37 171 = ALS 11933
  B0V: JM53,Morgan55,Hiltner56,Simonson68,Garcia89
  O9.5V: Cruz-Gonazalez74,Garrison76,Garmany82
  B9: Cannon (wow?!)
  It is not in the Maiz-Appelaniz O-star catalog. The majority say B0V.
  M91: V=7.419+-0.011, B-V=0.126+-0.012, U-B=-0.787+-0.005
  =>QBV=> (B-V)o=-0.281, (U-B)o=-1.053, E(B-V)= 0.407, T=29934.

# Weak standard? (at least for B0V)
HD 143275 = del Sco = HR 5953
  B0V: JM53,Jaschek64(most),Slettebak68,Thackeray66(B0Vnk),Morris61,Bertiau58
  B0: Cannon
  B0.5IV: Hiltner69,Jaschek78(Garrison67)
  B0.3IV: MK73,Houk88,Garcia89
  B1V: Wilson50
  B0IV: MK43.
  Originally B0V, but has been B0.3-0.5 since ~1970
  I'm assuming the most authoritative classification is B0.3IV (MK73)

HD 207538 = Cl Trumpler 37 1588 = ALS 12008 
  B0V: Morgan53,JM53,Morgan55,Hiltner56,Jaschek64(all),Simonson68,Garcia89
  O9.5V: Conti71,Conti73,Conti74,Garrison76
  O9III: Bisiachhi82,
  B3: Cannon
  Similar to HD 206183 -- Morgan called B0V, but others later moved to O9 or O9.5?
  M91: V=7.305+-0.014, B-V=0.324+-0.008, U-B=-0.640+-0.000
  =>QBV=> (B-V)o=-0.280, (U-B)o=-1.048, E(B-V)= 0.604, T=29695.

HD 46106 = HIP 31106 = Cl* NGC 2244 JOHN 5 (J0631+0501)
  B0V: Morgan65,Abt68,Walborn71
  B0.2V: Massey95,Wolff07
  B0.5V: Morgan53,Johnson62
  B1V: JM53
  B8: Cannon
  B1III: Voroshilov85
  Jaschek64 shows slew of types from O9.5V to B1V. Abt68 uses as B0V standard. 
  Too much disagreement to consider a useful standard.