X12 138 is a transaction set used to request and report testing results in an educational context. Educational institutions, testing organizations, and related entities send this transaction to request student test scores or to provide testing results to schools, credential evaluators, or other authorized recipients. The transaction set is typically initiated when an educational institution requires detailed testing information about students. Key segments include the BGN (Beginning Segment) which establishes the purpose and context of the request or report, the IN1 (Individual Identification) segment which identifies the student whose test results are being requested or reported, and the TST (Test Score Record) segment which contains the actual testing data and performance metrics.

Consider a scenario where Lincoln High School needs to verify testing results for transfer students applying to admission. The school sends an X12 138 transaction to the National Assessment Testing Center requesting test scores for five incoming students. The transaction includes student identification through the IN1 segment, demographic information through the DMG segment, and specifies the types of tests needed through the RQS segment. The testing center responds with an X12 138 containing the TST loop populated with actual test scores, subscores through the SBT (Subtest) segment, and any relevant statistical analysis. The receiving school uses this information to place students in appropriate courses and validate prerequisite completion.