OpenClinica uses Object Identifiers (OIDs, sometimes referred to as OpenClinica IDs) to link objects to one another, and enforce uniqueness within an instance of OpenClinica (with the exception of Rule OIDs, which must only be unique within a study).  We currently utilize OIDs for the following objects in OpenClinica:

  • CRFs
  • CRF Versions
  • Item Groups
  • Items
  • Measurement Units
  • Rules
  • Study Event Definitions
  • Studies
  • Sites
  • Study Subjects

Each OID generated by OpenClinica starts with a prefix based on the type of entity, followed by n characters taken from the start of the proper name of the object (alpha-numeric only and converted to all caps), plus a random number at the end if the OID already exists in the database. This random number is generally 3-4 characters long (345, 5678, etc). Each part of the OID is separated by underscores. Using this scheme, we generate the following OIDs for objects:

  • CRF: F + first 12 alpha-numeric characters in the CRF Name + random number if necessary (e.g. F_PHYSEXAM_7133)
  • CRF Version: the CRF OID + the first 10 alpha-numeric characters in the CRF Version Name + random number if necessary
  • Item Group: IG + first 5 alpha-numeric characters in the CRF Name + all the alpha-numeric characters in the Item Group Label + random number if necessary
  • Item:  I + first 5 alpha-numeric characters in the CRF Name + first 26 alpha-numeric characters in the Item Label + random number if necessary
  • Measurement Unit: MU + first 37 alpha-numeric characters in the measurement unit name + random number if necessary
  • Rule: generated by user input at the Import Rules stage of OpenClinica. Must be alpha-numeric and all caps (underscores allowed) with a maximum 40 characters. Each Rule OID must be unique within the study that it is uploaded to.
  • Study Event Definition: SE + first 28 alpha-numeric characters in study event definition name + random number if necessary
  • Study: S + first 8 alpha-numeric characters in the Studys Unique Protocol ID + random number if necessary
  • Site: S + first 8 alpha-numeric characters in the Studys Unique Protocol ID + random number if necessary
  • Study Subject: SS + all alpha-numeric characters in the Study Subject ID + random number if necessary. Each Study Subject OID will be unique within the entire OpenClinica instance. In ODM, Study Subjects are given a SubjectKey to identify a specific subject that is unique within the study, while OpenClinica Study Subject OIDs are unique across all studies in the instance.