Thx for your attention. The thing I trying to make it's Xen images builder,and when this software builds some image it takes input data (like hostname,IP, etc.... from a DB). So one appliance (that will be started from the image built by my system) may have multiple network interfaces, so element IP address may be repeated due to a multiple network interfaces, or user may want to add 2 images at once so whole form may be repeated with all its elements.