There are five kinds of expressions commonly used in writing articles, namely narration, description, lyricism, discussion and explanation. The diversity of expression forms the diversity of communication methods, and the double signature of the skin test performer uses the expression of discussion, mainly to make the article vivid and profound.

In nursing-related medical documents, double signing refers to the signature of two people, such as skin test results or blood transfusion examination orders. It needs two signatures. This situation is called double signing.