Parsing
Parsing turns a configuration file into a spec type.
Validation
Parsing, which precedes validation, ensures the spec is structurally correct.
Lowering
Once a spec is validated, lowering converts it into a config type.
Diagnostics
When parsing or validation finds a problem, it does not throw.
Layering
When an application reads its configuration, the values may come from more than one place.
Templates
A spec type already encodes the whole configuration surface.
Representations
Sometimes you need to see what your service loaded, which may differ from the file on disk.