I wished I knew, they may well have to be filled and pressurised.
I've got a little corrosion on the pipes which I wouldn't mind replacing. The mot bloke gave me an advisory on the brake pipes but I think he's got them mixed up with the ones for the shocks as they're very close.
Some other Toyota cars (4-runner is one) use a similar suspension setup (but the shocks are connected diagonally x-reas), I need to have a read of their workshop manuals to see if I can get any helpful information.
Here's some info on the x-reas that I've just found, I haven't found anything at all worthwhile for the reas in my previous searches.
Bare in mind that the two systems aren't connected in exactly the same way.
X-REAS Fitted to Toyota 4 Runner
I'm going to have another read in the morning as it's late and I'm off to bed.