In Jain tradition, a three‑day continuous fast is called “Attham” (also written Aatham/Attham tap). It means doing anashan/upvaas for three full days and then taking parna on the morning of the fourth day, usually with only boiled, filtered water allowed during daylight.

Notes by tradition:

• Shwetambar: Attham generally means 3 days of upvaas with only boiled water in fixed daytime hours; parna is done at a proper sunrise time, often coordinated with the Aatham (Ashtami) tithi, which is why it is called “Attham.”
• Digambar: The same three‑day fast is practiced as anashan with strict water discipline and careful parna timing; regional terms may vary, but 3‑day fast as “Attham” is commonly understood.

In short: “Attham” = a three‑day fast completed with proper parna, traditionally linked with the Ashtami (Aatham) lunar day.