IR segments left out because an endpoint coordinate (x0..z1) is Infinity or NaN (a consumer-built IR, or a float32 overflow). They are never uploaded: a non-finite position poisons the bounding sphere, so picking and frustum culling would break for the whole chunk. 0 for a well-formed IR. Core and the framework adapters do not surface this count yet (tracked with #518).
True when travel geometry was omitted because decimation is active.
1 = no reduction. Consumers MUST disclose values > 1 (§4.4).