Depth
Each layer of the value chain carries two depth levels: how deep the layer should go, and how deep the evidence currently goes. The table defines each level.
| Level | The test that must be passable |
|---|---|
| L0 | Name the layer and its function in one sentence. |
| L1 | Name the top three constraints, with units, and who the main actors are. |
| L2 | Reproduce the governing parametric relationship, and state its inputs and their ranges. |
| L3 | Do an independent order-of-magnitude calculation, and say where a published figure differs from it and why. |
Target and reached
Each layer page shows both levels. An important layer can have a target of L3 while the evidence gathered so far reaches only L1.
Where the 17 layers stand
| State | Layers | Which |
|---|---|---|
| Below target | 1 | XC03 |
| At target | 16 | VC01, VC02, VC03, VC04, VC05, VC06, VC07, VC08, VC09, VC10, VC11, VC12, XC01, XC02, XC04, XC05 |
| Beyond target | 0 | - |
What this means for anything you read here
Coverage is not complete while any layer sits below its target. Before relying on a record or an article, check the depth of the layers it draws on in the table above or on the value chain page.