Edit > Copy and Cut put the selected ruler guides on the clipboard,
with the selected objects or on their own. Pasting puts them on the
layer new art goes to, selected, in the same undo step: with objects
they move as the objects do; alone they keep their places, while Paste
in Place / in Front / in Back put them on the active artboard as they
lay on theirs, and Paste on All Artboards on every artboard.
Don Omondi
f3faa115c6