All of that common and true red tail mumbo jumbo is all pet trade talk. "common" usually refers to any of the common
BCI locales excluding the insular boas like
hog island etc but mostly refering to Colombian, Central American and Mexican. "True redtails" refers to
BCC locales. They seem to totally forget the others all together as there are many other subspecies of boa constrictor not included in either. Then again, anyone selling a Longicauda or Amarali or something is going to defenatly point out it's subspecies. There is no scientific ruling on what is "common" or what is "true" though as even the reference to "redtail" is all just pet trade lingo.