But there seem to be no clauses in the prospectuses for Greek government bonds that would trigger accelerated payment of the rest of what's owed on any particular bond in default or that would put other bonds into default: in the jargon, there are no accelerated payment or cross-default clauses.

BBC: Is a Greek default so bad for Greece?

Not paying the May 15 bond could have triggered so-called cross-default clauses, m eaning that holders of other bonds governed by foreign law that were also not swapped could have demanded immediate payment.

FORBES: The Value of Foreign Law in Investing: Greece Pays Out on English Bonds

So in theory if cross-default or accelerated payment clauses were unexpectedly to turn up in bond documentation, the Greek parliament could legislate to make them null and void.

BBC: Is a Greek default so bad for Greece?