<xsd:simpleType name="issnType">
<xsd:annotation>
<xsd:documentation>International Standard Serial Number. The is an identifier for articles and serial publications. The ISSN is defined by the ISO 3297 standard. The ISSN can be applied to series of books. A book belonging to a particular series will have both an ISSN (identifying the series) and an ISBN (identifying the given monograph as such).</xsd:documentation>
</xsd:annotation>
<xsd:restriction base="xsd:string">
<xsd:pattern value="ISSN[0-9]{4}-[0-9]{3}[0-9,X]{1}" />
</xsd:restriction>
</xsd:simpleType>
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