The dāll is the sign that directs the mind, while the madlūl is what it signifies. Confusing the two makes classification unreliable.
Example 1: The word “Zayd” is the sign; the person named is the signified.
Example 2: Smoke is the sign; the inferred fire is the signified.
Example 3: A standardized road sign is the sign; its agreed instruction is the signified.
Ask two questions: What is being perceived as a sign, and what does it lead us to know?