By Amy E. Feldman

PHILADELPHIA (CBS) – We know what a prenup is. But what’s a post nup?

READ MORE: 5 People Shot Near Temple University, Philadelphia Police Say

Soon to be former owner of the LA Dodgers Frank McCourt, in the midst of bankruptcy and divorce, may now file a lawsuit against his own lawyers for their big mistake in writing his post-nuptial.

What’s a post nup? It’s very much like a prenup, but it’s signed after the wedding. It usually lists the couples assets and liabilities and discusses who would retain what if the marriage should end.

READ MORE: Zack Wheeler K's 9 In 7 Shutout Innings, Phillies Top Padres 3-0

Couples get them for many reasons, including where a couple that had signed a prenup have a substantial change in fortune, where one spouse may get an inheritance, or where, like the McCourt case, the couple is contemplating divorce.

The McCourt’s post-nup should have said the Dodgers were “inclusive” of Frank McCourt’s separate property, but some documents used the word “exclusive” instead, changing the meaning of the whole thing, and making Frank liable to pay Jamie $131 million, instead of the ZERO she’d have been owed if it had been written right.

MORE NEWS: Republican Nomination For Pennsylvania U.S. Senate Race Uncertain As Thousands Of Mail-In Votes Still Being Counted

If you’re thinking of getting one, go to a reputable lawyer and ALWAYS read every document no matter who wrote it before you sign it.