Hi All.
I have a javascript function that changes the value of the next dropdown box from a list of multiple dropdown boxes based on an onchange event as shown below.
What I want to do is if the user selects for instance "software manufacturer" then it is never available again in any of the next dropdown boxes.
I can get this to work for the second checkbox but it comes back again for the 3rd checkbox and so on.

Hope it makes sense
var categories = [];
categories["startList"] = ["Software Manufacturer","Product Name","Product Version","Keep Existing","Ignore"]
categories["Software Manufacturer"] = ["Product Name","Product Version","Keep Existing","Ignore"];
categories["Product Name"] = ["Software Manufacturer","Product Version","Keep Existing","Ignore"];
categories["Product Version"] = ["Software Manufacturer","Product Name","Keep Existing","Ignore"];
 categories["Keep Existing"] = ["Software Manufacturer","Product Name","Product Version","Keep Existing","Ignore"];
 categories["Ignore"] = ["Software Manufacturer","Product Name","Product Version","Keep Existing","Ignore"];