defaults.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>picture</key>
	<string>https://example.com/path/to/image.png</string>
	<key>setOnlyOnce</key>
	<true/>
	<key>color</key>
	<string>3333FF</string>
	<key>scale</key>
	<string>stretch</string>
</dict>
</plist>