The standard IEC 61355-1 Classification and designation of documents for plants, systems and equipment[1] describes rules and guidelines for the uniform classification and identification of documents based on their characteristic content of information.
It is applied for all documents within the life cycle of a technical products like plants, systems or equipment.
A public access database IEC 61355 DB[3] is available in order to facilitate the individuation of the correct code to be applied to a document The document kind classification code consists of three code-letters A1, A2, A3, with the prefix "&".
The letter code A1 is optional, if all documents are from the same technical area.
The technical areas are: The main classes are: Table of main classes and subclasses Source: IEC 61355–1 Designation codes for document kind classification codes in power plants (DCC key) published by VGB PowerTech e.V.