The attachment object returned by Tabula has the following properties:

id	A unique identifier for the attachment
webOverlap	The % similarity overlap between the attachment and web sources
studentOverlap	The % similarity overlap between the attachment and other student submissions
publicationOverlap	The % similarity overlap between the attachment and publications
overlap	The overall overlap % returned from Turnitin for this attachment (also described as 'Similarity Index' by Turnitin)
similarity	A zero-indexed integer representing the similarity index returned by Turnitin: 0 - no matching words 1 - one matching word - 24% similarity index 2 - 25-49% similarity index 3 - 50-74% similarity index 4 - 75-100% similarity index
reportUrl	A URL to access the originality report in Turnitin