dired command on marked files

[Fabian Braennstroem]

Hi,

    I would like to use dired to create some plots using
    xmgrace/gracebat. My idea is to mark some files and plot
    them all into one diagram using something like:

    gracebat <file1> <file2> ... <file n> -pexec 'subtitle "<title>"'  
-hardcopy -hdevice EPS -printfile "<name>"
 
   Generally, I would use 'call-process' , but I have no clue, how I can create 
a call with variable number of files (depending on the marks).
   In the end, emacs should ask for the 'title' and 'name'.
 
   Does anyone have an idea or any suggestion, how I should do that?
   Thanks!

Greetings!
 Fabian