【Abstract】 The paper argues that the theory that opens out the nature of subject indexing process is required,if the process consists of a number of steps and elements and it is a range of interpretations,too.The paper points out that Peirce’s semiotics is the theory by which we may study and understand the nature of interpretation in subject indexing process.In recent years,there is a great interest in semiotics in library and information science field.The paper discusses some basic issues of semiotics and its use in information science.更多还原