The reference job is the baseline used to determine the relative differences to the current build. Several plugins that report build statistics (test results, code coverage, metrics, static analysis warnings) typically show their reports in two different ways: either as absolute report (e.g., total number of tests or warnings, overall code coverage) or as relative delta report (e.g., additional tests, increased or decreased coverage, new or fixed warnings). To compute a relative delta report, a plugin needs to select another build to compare the current results to (a so-called reference build). This reference build is obtained from the specified reference job.

In Multibranch Pipelines this parameter can be left empty: in these jobs, the plugin selects the build automatically from the associated job that builds the main target branch. For all other jobs, the last completed build of the current job will be used as reference build if the reference job is not specified.