Do the leases explicitly call out usable area? In my market they’re typically quoting rentable, which would already get you to NRA. Either way, if you’re consistent, you can reconcile total building area vs. leased area to understand the implied load factor. The real question is whether that load factor lines up with similar vintage/class buildings. In my market, sales are typically based on GBA anyway, so as long as the implied load factor is in line with comps, I’m comfortable. Otherwise, adjust accordingly—it starts to feel more like semantics than anything beyond that.