Knowing the origin of data (i.e., where the data was copied or created from)—its provenance—is vital for assessing the trustworthiness of contemporary scientific databases such as UniProt [16] and SWISSPROT [14]. Unfortunately, provenance information must currently be recorded manually, by added effort of the database maintainer. Since such maintenance is tedious and error-prone, it is desirable to provide support for recording provenance in the database system itself. We review a recent proposal for incorporating such support, as well as its theoretical properties.