<?xml version=“1.0” encoding=“UTF-8”?> <xsd:schema xmlns:xsd=“www.w3.org/2001/XMLSchema

targetNamespace="http://www.crossref.org/clinicaltrials.xsd"
xmlns="http://www.crossref.org/clinicaltrials.xsd">

<xsd:annotation>
    <xsd:documentation>  
     Linked Clinical Trials is a CrossRef initiative helping to connect the published literature to registered clinical trials associated with the research,

        - version 1.0 (initial release) September 24, 2015
    </xsd:documentation>
</xsd:annotation>

<xsd:element name="program">
    <xsd:annotation>
        <xsd:documentation>Accommodates deposit of linked clincal trials metadata. The clinical-trial-number value will
            be a string that must match a specific pattern appropriate for a given clinical trial registry. The
            registry is identified in the required attribute 'registry' and must be the DOI of a recognized registry
            (see http://dx.doi.org/10.18810/registries)
        </xsd:documentation>
    </xsd:annotation>

    <xsd:complexType>
        <xsd:sequence>
            <xsd:element ref="clinical-trial-number" minOccurs="0" maxOccurs="unbounded"/>
        </xsd:sequence>
    </xsd:complexType>
</xsd:element>

<xsd:element name="clinical-trial-number">
    <xsd:complexType mixed="true">
        <xsd:attribute name="registry" use="required">
            <xsd:annotation>
                <xsd:documentation> The clinical trial identifier related to the article.
                </xsd:documentation>
            </xsd:annotation>
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:maxLength value="200"/>
                    <xsd:minLength value="12"/>
                    <xsd:pattern value="10.18810/[a-z-]+"/>
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
        <xsd:attribute name="type" use="optional">
            <xsd:annotation>
                <xsd:documentation> Used to identify the article publication date in relation to the issuance of the trial results
                </xsd:documentation>
            </xsd:annotation>
            <xsd:simpleType>
                <xsd:restriction base="xsd:string">
                    <xsd:enumeration value="preResults"/>
                    <xsd:enumeration value="results"/>
                    <xsd:enumeration value="postResults"/>
                </xsd:restriction>
            </xsd:simpleType>
        </xsd:attribute>
    </xsd:complexType>
</xsd:element>

</xsd:schema>