Order of curves in pdf or svg

ok - great - thanks.
just if others come by to this topic - there is a nice example to get started

one think i am still missing:
is there something like lowest / highest DisplayOrder to directly query ?
Where does “bringToFront” get the highest Number from ? to i have to scan all objects in the document ? or is this query already implemented somewher in rhino-common.
(can t find it)

thanks