<type name="Magento\Ui\Config\Reader\Definition">
    <arguments>
        <argument name="fileName" xsi:type="string">
            etc/definition.xml
        </argument>
        <argument name="converter" xsi:type="object">
            Magento\Ui\Config\Converter
        </argument>
        <argument name="fileResolver" xsi:type="object">
            Magento\Ui\Config\Reader\FileResolver
        </argument>
        <argument name="schemaLocator" xsi:type="object">
            Magento\Ui\Config\Reader\Definition\SchemaLocator
        </argument>
        <argument name="idAttributes" xsi:type="array">
            <item name="/components/(.*)/argument" xsi:type="string">
                name
            </item>
            <item name="/components/(.*)/argument(/item)+"
                  xsi:type="string">
                name
            </item>
        </argument>
    </arguments>
</type>

This is a type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This configuration tells the Object Manager that when a user wants a Magento\Ui\Config\Reader\Definition object that the following arguments should be used in the foo object's constructor.

• $fileName = "etc/definition.xml";
• $converter = new Magento\Ui\Config\Converter (...)
• $fileResolver = new Magento\Ui\Config\Reader\FileResolver (...)
• $schemaLocator = new Magento\Ui\Config\Reader\Definition\SchemaLocator (...)
• $idAttributes = [...items...];