Yes — in the Digambar tradition, the last day of Paryushan / Das Lakshan Parva is celebrated as Uttam Kshama, also called Shama Parv or Kshamavani.

So if 26 September 1988 was the concluding day according to the Digambar panchang/tithi used in your area, then yes, it would be the end day of Paryushan / Shama Parv.

In Jain practice, this day is dedicated to:

• asking forgiveness
• forgiving others
• practicing humility and peace

Different regions and panchangs can sometimes show a one-day variation based on tithi and local observance.