You can add things in your custom list without putting anything on the test plate. There are two algorithms used for encoding and they are both used at all times for encoding into the Custom Library. One is for whatever is put on the plate and one is for the words used to name what is on the plate. Because the name algorithm is using the words you use to label the item, it is very important that you are accurate in the label. The more specific the name and description, the better the encoding of the energy pattern for that item.
Both methods (item on the plate or no item on the plate) are equally effective so it does not matter which way you do it.
As you can imagine, this proprietary information is one of the main things that sets us apart from other systems so we do not give any details about the algorithms.