RELATION IS DESCRIPTOR
The RELATION IS DESCRIPTOR is a word or phrase that states object 1's relation is object 2. PhpGedView includes the following relationships; attendant, attending, best_man, bridesmaid, buyer, circumciser, civil_registrar, friend, godfather, godmother, godparent, informant, lodger, nurse, priest, rabbi, registry_officer, seller, servant, twin, twin_brother, twin_sister, witness. You can use other values, but to do so you must edit the raw GEDCOM record.
For example you would read the following as "Joe Jacob's great grandson is the submitter pointed to by the @XREF:SUBM@":
0 INDI 1 NAME Joe /Jacob/ 1 ASSO @<XREF:SUBM>@ 2 RELA great grandson