User-defined metrics in Grid Control

I want to create a user-defined metric to return some value for specific targets (disks).

The script would do its thing and return the result as "em_result=1234".

My problem is that the same script is used to do the processing on all target disks. How can I pass it a parameter (the name of the disk it needs to process) ?

I just can't see how to do this in the doc.

Oracle 10.2 on OpenVMS

Thanks

-- 
Syltrem
http://pages.infinit.net/syltrem (OpenVMS information and help, en français)