Container element for one or more contributors in a bibliographic reference.
Any combination of:
Text, numbers, or special characters
<anonymous> Anonymous
<collab> Collaborative (Group) Author
<name> Name of Person
<name-alternatives> Name Alternatives
<string-name> Name of Person (Unstructured)
<aff> Affiliation
<aff-alternatives> Affiliation Alternatives
<etal> Et Al.
<role> Role or Function Title of Contributor
<x> X - Generated Text and Punctuation