ISO 4063:2009 establishes a nomenclature for welding and allied processes, with each process identified by a reference number. ISO 4063:2009 covers the main groups of processes (one digit), groups (two digits) and sub-groups (three digits). The reference number for any process has a maximum of three digits. This system is intended as an aid in computerization, drawings, the drafting of working papers, welding procedure specifications, etc.