539a7e1a_RSS_Field_Descriptions__Required___Optional
[Name of Field] Source [Description of Feed] If the item was obtained from another feed, then the source feed's information can be entered here. Source The title of the feed that the item came from. URL Optional The URL to the RSS feed that the item came from. [Required / Optional] 
Including a Source with your feed is optional. However, if you enter information into the source field, then you must also include information in the URL field.
RSS Field Descriptions
Required / Optional