The *.artdef files inside the 'Sid Meier's Civilization VI\Base\ArtDefs' directory are just normal xml.
This is the SkyBox.artdef.
This is the SkyBox.artdef.
Code:
<?xml version="1.0" encoding="UTF-8" ?>
<AssetObjects::ArtDefSet>
<m_Version>
<major>3</major>
<minor>0</minor>
<build>184</build>
<revision>899</revision>
</m_Version>
<m_TemplateName text="SkyBox"/>
<m_RootCollections>
<Element>
<m_CollectionName text="SkyBox"/>
<Element>
<m_Fields>
<m_Values>
<Element class="AssetObjects::BLPEntryValue">
<m_EntryName text="Skybox"/>
<m_XLPClass text="SkyBoxTexture"/>
<m_XLPPath text="SkyBox.xlp"/>
<m_BLPPackage text="SkyBox"/>
<m_LibraryName text="SkyBoxTexture"/>
<m_ParamName text="SkyBoxTexture"/>
</Element>
</m_Values>
</m_Fields>
<m_ChildCollections/>
<m_Name text="SkyPlane"/>
</Element>
</Element>
</m_RootCollections>
<m_BLPReferences/>
</AssetObjects::ArtDefSet>