:'''2''' Difference

===<span id="a"></span>$a Standard Number===

to type.

===<span id="b"></span>$b Qualification===

relationship of a number or code to a set or to a particular volume.

===<span id="c"></span>$c Additional codes following standard number or codes===

Contains any coded suffix to the identifier.

===<span id="d"></span>$d Terms of Availability and/or Price===

The price of the item and any comment on its availability.

===<span id="z"></span>$z Erroneous Number or Code===

and in this instance cancelled or it may have been incorrectly printed.

==Related Fields==