Yeah, this is probably meant to be used for their "Office Store" Add-ins. You could think of them as web apps that are "iframed" into Office applications. They

Yeah, this is probably meant to be used for their "Office Store" Add-ins. You could think of them as web apps that are "iframed" into Office applications. They have a store full of these web add-ins at https://store.office.com/en-001/appshome.aspx?ui=en-US&rs=en-001&ad=US https://store.office.com/en-001/appshome.aspx?ui=en-US&rs=en... and dev docs at https://dev.office.com/docs/add-ins/overview/office-add-ins https://dev.office.com/docs/add-ins/overview/office-add-ins