Umatic variants

[DVtyro]

Googling around, I am still not sure I got it right:

• First there was the Umatic, which in retrospect became low-band
• Then Sony created High-band, but for 625/50 only. Did Sony give all these machines "BVU" prefix? Or only some of these machines? High band 625/50 means BVU?
• Then Sony created SP, both for 525/60 and 625/50. Were any SP machines ever called BVU? Or BVU was used strictly for pre-SP 625/50 high-band machines? No BVU in the US? If there were BVU machines for the US, then they were SP?