The "atom:entry" element Per RFC4287
The "atom:entry" element represents an individual entry, acting as a container for metadata and data associated with the entry. This element can appear as a child of the atom:feed element, or it can appear as the document (i.e., top-level) element of a stand-alone Atom Entry Document. atomEntry = element atom:entry { atomCommonAttributes, (atomAuthor & atomCategory & atomContent? & atomContributor & atomId & atomLink & atomPublished? & atomRights? & atomSource? & atomSummary? & atomTitle & atomUpdated & extensionElement*) } This specification assigns no significance to the order of appearance of the child elements of atom:entry. The following child elements are defined by this specification (note that it requires the presence of some of these elements): o atom:entry elements MUST contain one or more atom:author elements, unless the atom:entry contains an atom:source element that contains an atom:author element or, in an Atom Feed Document, the atom:feed element contains an atom:author element itself. o atom:entry elements MAY contain any number of atom:category elements. o atom:entry elements MUST NOT contain more than one atom:content element. o atom:entry elements MAY contain any number of atom:contributor elements. o atom:entry elements MUST contain exactly one atom:id element. o atom:entry elements that contain no child atom:content element MUST contain at least one atom:link element with a rel attribute value of "alternate". o atom:entry elements MUST NOT contain more than one atom:link element with a rel attribute value of "alternate" that has the same combination of type and hreflang attribute values. o atom:entry elements MAY contain additional atom:link elements beyond those described above. o atom:entry elements MUST NOT contain more than one atom:published element. o atom:entry elements MUST NOT contain more than one atom:rights element. o atom:entry elements MUST NOT contain more than one atom:source element. o atom:entry elements MUST contain an atom:summary element in either of the following cases: * the atom:entry contains an atom:content that has a "src" attribute (and is thus empty). * the atom:entry contains content that is encoded in Base64; i.e., the "type" attribute of atom:content is a MIME media type [MIMEREG], but is not an XML media type [RFC3023], does not begin with "text/", and does not end with "/xml" or "+xml". o atom:entry elements MUST NOT contain more than one atom:summary element. o atom:entry elements MUST contain exactly one atom:title element. o atom:entry elements MUST contain exactly one atom:updated element.