What is meant by required-api: param name=”#target” in config.xml file of AGL widgets?

I am trying to understand various available AGL specific options that we can give in config.xml and I am referring to the link below

https://docs.automotivelinux.org/docs/en/halibut/apis_services/reference/af-main/2.2-config.xml.html

This is the sample config.xml file

<feature name="urn:AGL:widget:required-api">
<param name="#target" value="main" />
<param name="gps" value="auto" />
<param name="afm-main" value="link" />
</feature>

what is the need for <param name="#target" value="main" /> and what it meant?