2. Implicit features or well-known equivalents 

A document takes away the novelty of any claimed subject-matter derivable directly and unambiguously from it, including any features a skilled person would consider implicit in what is expressly mentioned in it. For example, a disclosure of the use of rubber in circumstances where its elastic properties are clearly used even though this is not explicitly stated takes away the novelty of the use of an elastic material. The limitation to subject-matter "derivable directly and unambiguously" from the document is important. Thus, when considering novelty, it is not correct to interpret the teaching of a document as embracing well-known equivalents which are not disclosed in the documents; this is a matter of obviousness.