ignoredisk --only-use and zerombr

Does anyone happen to know if zerombr respects ignoredisk 
--only-use=/dev/foo, or if it is independent.

That is, if I specify a disk first and then issue the zerombr command 
for example:

//snip

ignoredisk --only-use=/dev/sda
zerombr

//end snip

will zerombr only operate against /dev/sda, or will it operate against 
anything it can?


The description for zerombr states "If zerombr is specified, _any_ disks 
whose formatting is unrecognized are initialized", which leads me to 
believe it doesn't, but I would like to know for sure.

Thanks in advance,

--Eric