PSLink.h

typedef enum { 
    PSLinkToOther, // Any other kind not covered by this enumeration 
    PSLinkToRSS, // RSS feed 
    PSLinkToAtom, // Atom feed 
    PSLinkToAtomService, // Atom Publishing Protocol service document 
    PSLinkToFOAF, // FOAF file (social network data) 
    PSLinkToRSD, // RSD (really simple discovery) document for locating Blogger API 
    PSLinkToSelf, // Definitive URL of this very resource 
    PSLinkToAlternate // Some other alternate representation (usually an HTML page) 
} PSLinkKind;