3 Metadata Schemes, Structures, and Encoding First, it is important not to confuse metadata structures and schemes with how they are encoded for use within a digital system. This is easy to do and is one of the most common causes of misunderstanding. It is important to be clear that what a metadata element is (a list of elements in a metadata structure or dic- tionary) and how it is used (metadata scheme) has nothing whatsoever to do with how it is encoded for that use. Example encoding schemes are key-length-value (KLV), used for wrapping video or audio data into computer files between media servers, and eXtensible Mark-up Language (XML), frequently used for wrapping metadata into computer files between databases in the form of XML schema. Metadata Schemes and Structures Earlier, we touched on the differences between data, information, and knowledge.