Evidence levels

What each level L1 to L5 demonstrates, and what it does not.

RestorSignal organizes the depth of a verification into five cumulative levels, L1 through L5. Each level adds checks more demanding than the one before it; the level reached by a test is the highest level demonstrated — never an average, and never an estimate. This page restates the normative definition of the levels as set out in the RS-RVP-01 reference framework.

L1 — Artifact accessibility

L1 establishes that the artifact can be read and identified: presence, opening, size, readability, an identifiable format, a computable cryptographic fingerprint.

What L1 does not demonstrate: that the artifact can actually be used, or that a restore is possible at all. A perfectly readable file can still be structurally invalid, or correspond to an empty backup.

L2 — Structural integrity

L2 establishes that the artifact has the minimal structural characteristics needed for processing: an extractable archive, the expected structure, essential metadata present, no blocking structural error, compatible syntax where relevant.

What L2 does not demonstrate: that a technical restore will succeed. Structure can be valid while the data inside is incomplete or the application content unusable.

L3 — Technical restore

L3 requires an actual restore operation: a real database import, rebuilding a CT or VM, starting the engine or the restored system, minimal technical access after the restore.

What L3 does not demonstrate: that the restored services actually work, or that they respond to requests. A system can start without its application services being operational.

L4 — Functional validation

L4 adds functioning checks: an active service, the expected port, a responding SQL engine, an accessible HTTP endpoint, an available technical API, the expected filesystem mounted.

What L4 does not demonstrate: that the application meets the client's business requirements. A service can respond correctly at a technical level while being functionally wrong from a business standpoint.

L5 — Application validation

L5 adds a predefined application or business protocol, defined by the client, an MSP, an integrator, or adapted from a RestorSignal template. The normative wording is:

L5 — the restore satisfied the required technical checks and all mandatory checks of the application protocol identified in the evidence package.

What L5 does not demonstrate: L5 does not mean the entire application's functionality was tested. The level reached is strictly bounded by the scope covered by the application protocol identified in the evidence package — no more, no less.

The roll-up rule to a level's status

A level is only positively obtained if 100% of its mandatory controls are PASS, subject to the NOT_APPLICABLE exceptions the protocol explicitly allows. An ERROR on a mandatory control does not silently block the result: it produces an INDETERMINATE level status, distinct from a failure (FAIL) and never treated as equivalent to a success (PASS). See Result statuses for the full vocabulary of control and level statuses.