In governments with a hemicycle shaped parliment, left wing parties and right wing parties tend to sit on the side of the parliment that more closely matches their ideaology.
However I was wandering how parties decide between them who get's to sit where?
For instance looking at the Belgian parliment which has two socialist parties Vooruit (the Flemish socialist party) sits to the right of Parti Socialiste (the Walloon socialist party) even though their two ideaologies should be very similar.
I'm sure there are other situations similar to what I've listed above, how do they usually handle this?
If this differs country by country could I have examples? at least one of how it's done in Belgium.