An interesting question, but I am supporting hsbcn, and would like to add following:
Having been involved in both supplying, servicing and describing PSVs, supplying tags and datasheets, I have seen too many datasheets and tags giving the information of 'everything you need except the necessary information you need to supply service, parts or a new product'.
Today you have, on the technological front end, the possibillity of electronic tags, giving by portable electronic readers/PCs or inline or by radio information to control office, all relevant information, including full description of make, type, dimension, drawings, process conditions, performance and track record etc.
In that case a written tag need only give a cross reference to the electronic (or written) record, plus identify the placement of the product if removed for repair or service.
This is then the minimum requirement. If you need anything more, this should be as described by hscbn on a 'need to know' basis.
The tag content and form is often 'standardized', but by the companies. The reason is, as described above, the plants overall current system status for detailed part/machinery information record. This could be everything from full electronic to almost non-exsistent records. If necessary, the starting point could then be revising the record-keeping and tracing system.
Standards, rules and regulations on a 'general or higher' level, from outside the company, will in my experience be limited, requiring tagging for components (if included) for tracing the component information, which could be recorded 'anywhere'.
(Note: Theese comments on tagging to be seeen apart from 'marking/factory signs' and the marking of products which is required in production standard and codes for the product itself, or for certain plants (atomic powerplants????).
