The top level of a product taxonomy, ten to thirty of them, at which whitespace, products per customer and cross-sell are computed. Families sit beneath, SKUs beneath those. Every SKU has one family and every family one line, dated, and revenue sums identically at every level.
Whitespace on lines; catalogue fit on families; stock-outs and price on SKUs.
A family moved to another line gets a dated row. Overwriting restates every product measure to the start.
The top level of the product taxonomy, ten to thirty entries that a salesperson would recognise as a conversation. Whitespace, products per customer and cross-sell are all counted at this level.
A distributor with 60,000 items groups them into fourteen lines. Whitespace is a list of customer and line pairs, not customer and item pairs.
Counting at item level. Every customer has tens of thousands of gaps and none of them is a conversation.