And you would be correct...
The " Box " is the same format as Danzon ,which is/was the original form of Rumba.
This box style was taught in the UK until the late 40s, and is still taught in the US as part of the Bronze sylab.. The Intern style Rumba is based on Bolero, again, still taught in the US.
I use the Box format for my social class students ( AND with original cuban music )..-