Greece's parliamentary system

Was reading about today’s Greek parliamentary vote for austerity measures and came across this:

"*Twenty two PASOK MPs and 21 New Democracy deputies voted against the bill. In both cases, thoe lawmakers were expelled from their parties.

Former Transport Minister Makis Voridis and Deputy Mercant Marine Minister Adonis Georgiadis went against the line of their party, Popular Orthodox Rally (LAOS), by voting for the bill. Both were expelled*."

Now this is interesting. I wonder (and would appreciate if someone tells me) whether the expulsion is automatic for voting against the party line in an important vote. Was this by any chance considered a “vote of confidence”?

And second question - Greece apparently has a bizarrely complex system to elect its parliament that combines multi-seat constituencies, single-seat constituencies and party lists, but I presume that the expelled-from-party representatives are not expelled from the parliament and are still full voting members. So what do they do - form separate fractions?

This has nothing to do with parliamentary procedure in Greece (or almost anywhere else in the world) but everything to do with the individual party’s rules and ad-hoc decisions. The party probably has a whip which tells members which votes they’re free to dissent on and which require party unity; members can ignore this advice at the peril of various sanctions, up to and including expulsion from the party.

They do whatever they want to. They can sit as independents and not talk to each other, create an informal voting bloc, or formally establish themselves as a new party (provided they’re able to meet whatever legal requirements there are).