ANSI/ISA-5.1-1984, and then reaffirmed in 1992. This revision extensively changes the format of ANSI/ISA-5.1-1984 (R 1992). Clauses 1, 2, and 3 are essentially the same as previously written with some additions and modifications. Clauses 4, 5 and 6 and informative Annexes A and B are new or extensively revised.
The letters in Table 4.1 - Identification letters shall have the mandatory meanings assigned except the user shall assign:
- Variables to the User's Choice letters when such letters are used
- Meaning to the blanks (undesignated letters) when additional functions or modifiers are assigned
Loop Identification letters and numbers should (informative and not mandatory) be assigned in accordance with one of the 9 Loop Numbering Schemes.
Therefore, this ISA-5.1 revision supports significant flexibility to allow users to be in full compliance with this National Consensus Standard.
However, many organizations must accommodate legacy requirements for their existing data. This application has therefore been designed to accommodate extensive administrative configurations beyond the default ISA standard configurations, as well as unvalidated user inputs that comply with the Project's maximum length requirement. Such flexibility should accommodate most project's need for consistent identification Number generation!