A contentful region's profile: what the block IS, and one line per series inside it.
summary rides the region's address line; series are the indented lines beneath it.
summary
series
One line per column (or row); empty for cell and list, whose profile is in summary.
cell
list
The one-line description that sits beside the address — header row 1, or a 1×1's value.
header row 1
A contentful region's profile: what the block IS, and one line per series inside it.
Remarks
summaryrides the region's address line;seriesare the indented lines beneath it.