"normal", "elite", "rareelite", "worldboss", ...; undefined when hidden.
The creature type in lower case ("undead", "mechanical"); undefined when the client hides it.
The unit's GUID; undefined when the client hides it (an NPC's GUID is secret on restricted maps).
Health in percent; undefined when the client hides it.
How far the unit is, as a band of yards: [nearest, farthest]. From the client's measure for group members, else from the interact distances (in combat the client refuses these for a friendly unit). Undefined ends are unknown.
How the unit stands to the player: 1 hated ... 4 neutral ... 8 exalted; undefined when the client hides it.
The threat state of the player on the unit (2 or 3: the player has aggro); undefined when hidden or not on the table.
Dead; undefined when the client hides it.
A living unit the player cannot attack and that is friendly to them.
In combat; undefined when the client hides it.
Is the unit on the player's threat table at all? Undefined when the client hides it.
Are the two tokens the same unit? Undefined when the client hides it (compound tokens in combat).
Within the duel distance (about 10 yards); undefined when unknown.
Within the inspect distance (about 28 yards); undefined when unknown.
The unit is casting or channeling; a readable "not interruptible" marks the cast shielded.
The unit's power of a kind (0 mana, 1 rage, 3 energy): current and maximum; undefined when hidden.
Hostile and attackable (nameplates); a hidden answer counts as no.