What kind of source is commentary and digest in Hindu Law?

Commentaries and digests are an "ancient source" of Hindu law, along with Shruti, Smriti and custom. Commentaries explain a particular Smriti, as the Mitakshara does the Yajnavalkya Smriti, while digests bring together the rules of several Smritis. The modern sources are justice, equity and good conscience, precedent and legislation.