Indicates for the associated <isbn> and <issn> elements whether the number provided is the primary number when multiple numbers are given. This attribute will be typically be used to indicate that the number is not the primary one, that is, the attribute’s value will be “no”.

Attribute Values

In Elements

<isbn> ISBN
<issn> ISSN
Value Meaning
no The number is not the primary number.
yes The number is the primary number.
Restriction: This attribute may be specified if the element is used.