Can you tell me the format or direct me to the documentation that defines the format, please? I have been unable to find this.
In recent versions, you can simply copy/paste a list of IPs or hostnames into the wizard. In <=9.5, this KB should assist: http://knowledgebase.solarwinds.com/kb/questions/724/How+do+I+use+a+seed+file+to+discover+devices+and+import+them+into+Orion+NPM%3F