page_layout.xsd

<?xml version="1.0" encoding="UTF-8"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:include schemaLocation="urn:magento:framework:View/Layout/etc/elements.xsd"/>
    <xs:include schemaLocation="urn:magento:framework:View/Layout/etc/head.xsd"/>
    <xs:include schemaLocation="urn:magento:framework:View/Layout/etc/body.xsd"/>

    <xs:complexType name="pageLayoutType">
        <xs:sequence minOccurs="0" maxOccurs="unbounded">
            <xs:element ref="referenceContainer" minOccurs="0" maxOccurs="unbounded"/>
            <xs:element name="container" type="containerType" minOccurs="0" maxOccurs="unbounded"/>
            <xs:element ref="update" minOccurs="0" maxOccurs="unbounded"/>
            <xs:element ref="move" minOccurs="0" maxOccurs="unbounded"/>
            <xs:element name="head" type="headType" minOccurs="0" maxOccurs="unbounded"/>
            <xs:element name="body" type="bodyType" minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
    </xs:complexType>

    <xs:element name="layout" type="pageLayoutType">
        <xs:unique name="containerKey">
            <xs:selector xpath=".//container"/>
            <xs:field xpath="@name"/>
        </xs:unique>
    </xs:element>
</xs:schema>