Fourth Avashyak: Pratikraman.

• In the Śvetāmbara Avashyak sequence (1) Samayik, (2) Chauvisantho, (3) Vandan, (4) Pratikraman, (5) Kayotsarga, (6) Pratyakhyan — the fourth is Pratikraman.
• What it means/what is done: sincere self‑review and repentance (alochana–pratikraman) for faults of thought, speech, and body; acknowledging lapses in vows and conduct, asking forgiveness (Micchāmi Dukkaḍaṃ), and “returning” from transgressions.
• Tradition note: Digambara lists of “six essentials” are different, but the act of pratikramana (repentance) is practiced there too. In the Śvetāmbara Avashyak order specifically, the fourth is Pratikraman.

For a simple overview of Pratikraman and the six Avashyaks: | Easy English outline: