block-progression-dimension property

W3C CR-XSL-20001121, Section 7.13.1. "block-progression-dimension", states:
"This property specifies the block-progression-dimension of the
content-rectangle." It seems unclear as to how this should be interpreted. 

If the block-progression-dimension is set to a fixed length, can multiple
areas be generated by a formatting object to which this property applies? Or
can only one area be generated with the specified
block-progression-dimension? 

If multiple areas can be generated, does each area have a
block-progression-dimension of the specified length? Or is the sum of the
block-progression-dimensions equal to the property's computed value? 

Similar questions probably also apply to the inline-progression-dimension
property.