...use split /(?:...)+/ to 'combine' them into one 'split-point'. and then grep for empty lines i.e. grep /./, ..., since the first element is still empty, so might as well use grep /./, ... on the lot to start with.

I tried the zero capture approach, but a) transposed the '?' and the ';' and b) didn't use '+' ... doh !!!

Update:

To reduce any confusion, the transposition to which I referred in the above was entirely down to the paucity of my typing i.e. I typed ':?' instead of '?:' and didn't notice .oO(Maybe I ought to use a larger font...) ;-)