Authorship must be earned through a substantial contribution. Traditionally, project initiation and framing, data analysis and interpretation, software or algorithm development, and manuscript preparation are all authorship-worthy contributions, and remain so for TERRA REF manuscripts. However, TERRA REF collaborators have also agreed that collaborators who lead a site from which data are being used in a paper can also opt-in as co-authors, under the following conditions: (1) the collaborators' site has contributed data being used in the paper's analysis; and (2) that this collaborator makes additional contributions to the particular manuscript, including data analysis, writing, or editing. For co-authorship on opt-out papers, each individual must be able to check at least two boxes in the rubric in addition to contribution to the writing process. These guidelines apply equally to manuscripts led by graduate students.