The Segment Reporting Builder

Help me build internal segment reporting so I can see where I make money.

The business segments: [BY PRODUCT / REGION / CHANNEL / CUSTOMER TYPE]
The data I have: [DESCRIBE]

Provide:
1. How to structure P&L by segment (revenue, direct costs, contribution,
   allocated overhead)
2. Which costs to allocate vs keep central, and why the allocation
   choices matter
3. The profitability picture by segment and where it's surprising
4. The traps in segment reporting (arbitrary allocations driving bad
   decisions)
5. What the reporting suggests about where to focus and where to fix

Build it to inform decisions, and flag where an allocation could mislead
rather than reveal.