SmartNews (https://www.smartnews.com) is a free mobile news aggregation app for iOS and Android.
Publishing partners can distribute articles more rapidly with greater control over presentation if they provide a SmartFormat feed to SmartNews.
The SmartFormat varient of RSS feed has the following additional fields.
It can be accessed using the following parameter /?feed=smartformat after the path. For example: https://www.domain.com/?feed=smartformat
Official Documentation on SmartFormat