A7IV

MK73, Morgan71, MorganAbt72, and Cowley74 list iot UMa (HR 3569) as the A7IV standard

GarrisonGray89 list HR 3270 as their low-vsini A7IV standard, and iot
UMa as their high-vsini A7IV standard.

JM53 and Houk88 do not list a A7IV standard. JM53 lists Altair (alf Aql)
and alf Cep as non-standard A7IV/V stars. 

Morgan65 classified only one Hyad as a subgiant: HD 28319 (=
BD+15_632)as a A7IVn.  But it is called A7III by MK78 and all
subsequent literature (GrayGarrison89, Gray89, Gray01).

# Primary Standard
HD 70060 = HR 3270 (J0818-3639, V=4.4)
  A7IV: GrayGarrison89(low-vsini stan.)
  A7III: Jaschek64(most),deVaucouleurs57,
  A4(M)A5-A7: Houk82
  A5: Cannon
  A5/7: Loden69
  Houk82 notes "HR 3270; |V SIN|I=130; OR COULD BE A5/7 III"
  Plx=34.93+-0.18 (HIP2), Vmag=4.44, B-V=0.222. HIP2 =>
  Mv=2.16, and only 0.03 mag above main sequence. 

# Weak Standard. 
HD 76644 = iot UMa = 9 UMa = HR 3569 = HIP 44127
  A7V: JM53,Jaschek64(all),Cowley67,Cowley69(stan),Barry70,Gray03(A7Vn)
  A7IV: MorganAbt72,MK73,Cowley74(stan),Garcia89,GrayGarrison89(high-vsini stan.)
  A6V: Palmer68
  A5: Cannon
  B-V(HIP)=0.223, dMv=+0.16... so it is probably a dwarf
  Spectroscopic binary. Basically A7V until ~Morgan72, then A7IV since until Gray03
  Beware! M2V component "BC" 3.7" away. 
  Should be considered "A7Vn".