<?xml version="1.0"?>
<ruleset name="outer/edge Magento coding standard">
    <config name="installed_paths" value="vendor/outeredge/coding-standards,vendor/magento-ecg/coding-standard"/>

    <arg value="p"/>
    <arg name="colors"/>
    <arg name="extensions" value="php"/>

    <rule ref="EcgM2"/>
    <rule ref="OuterEdge"/>

    <exclude-pattern type="relative">vendor/*</exclude-pattern>
</ruleset>

<?xml version="1.0"?>
<ruleset name="outer/edge Magento coding standard">
    <config name="installed_paths" value="vendor/outeredge/coding-standards,vendor/magento-ecg/coding-standard"/>

    <arg value="p"/>
    <arg name="colors"/>
    <arg name="extensions" value="php"/>

    <rule ref="EcgM2"/>

    <rule ref="OuterEdge">
        <exclude name="PSR2.Classes.PropertyDeclaration.Underscore" />
    </rule>

    <exclude-pattern type="relative">vendor/*</exclude-pattern>
</ruleset>

Allow underscores as Magento 2 does
Allow underscores as Magento 2 does