Capability
Capability describes what an entity can credibly do
Specification-sourced: quoted from the governing specification, pending the applicable specification-owner approvals. The specification controls.
In plain words
Capability is competence: what an entity can credibly do, stated with the evidence that makes it credible. It does not say how much is free to commit.
What it is not
Capability ≠ Capacity
Capability says what an entity can credibly do; Capacity says how much of it is actually available under stated conditions. Capabilities and Capacity · Concept Paper (source: 01 §4.3)
Capability ≠ Authority
Capability is what an entity can credibly do; Authority is whether it may perform a specific operation in context, and Capability never implies Authority. Authentication Is Not Authority · Canonical Model & Protocol (source: 04 §20.1)