EN 61346-2:2000

Introduction
1 Scope
2 Normative references
3 Definitions
4 Classification principle
5 Classification of objects according to purpose or
  task and associated letter codes
6 Classification of infrastructure objects and
  associated codes
7 Subclasses
Annex A (informative) Basic requirements for the
        definition of letter codes indicating the
        types of objects
Annex B (informative) Object-classes related to a
        generic process
Annex C (informative) Object-classes related to objects
        in a generic infrastructure
Annex D (informative) Letter symbols for measured or
        initiating variables
Annex ZA (normative) Normative references to international
         publications with their corresponding European
         publications
Figure 1 - The basic process concept
Figure 2 - Classification of objects and relevant letter
             codes in a measuring circuit
Figure A.1 - Constituent objects
Figure B.1 - Object-classes related to a process
Figure C.1 - Object-classes related to objects in a
             generic infrastructure
Table 1 to 3

Defines object classes and associated letter codes for these classes to be used in reference designations. Applicable in all technical areas and may be applied at any position in a tree-like structure set up in accordance with EN 61346-1