Sahih li-dhatihi: uprightness, continuity, freedom from disqualifying defects and anomalies, and full precision; the chain is intrinsically sound.
Hasan li-dhatihi: the same other requirements with somewhat lighter but adequate precision; the chain is intrinsically acceptable.
Sahih li-ghayrihi: an intrinsically hasan report reaches sahih level through effective corroboration from independent routes.
Hasan li-ghayrihi: a report with a compensable weakness is raised to a cumulative hasan grade through credible support.
Key distinction: *li-dhatihi* refers to the chain's own adequate qualities, while *li-ghayrihi* refers to strengthening from outside. *Hasan* and *sahih* describe grades of acceptance. Every actual case still requires a separate verification of the conditions.