[Info-vax] backup oddity

[Phillip Helbig undress to reply]

>From sys$specific:[000000], the command

   $ dir [...]*.*;*/exc=(syscommon.dir,[.syscommon...]*.*;*) 

works as expected, whereas 

   $ backup [...]*.*;*/exc=(syscommon.dir,[.syscommon...]*.*;*)

takes the syscommon.dir and the directories and subdirectories within it
as well. 

Why is this the case?

How can I achieve the expected result, without doing it "by hand"?