att.rdgPart attributes for elements which mark the beginning or ending of a fragmentary manuscript or other witness. [12.1.5 Fragmentary Witnesses]
Moduletextcrit — Critical Apparatus
MemberslacunaEnd lacunaStart wit witEnd witStart
wit(witness or witnesses) contains a space-delimited list of one or more sigla indicating the witnesses to this reading beginning or ending at this point.
Status Optional
Datatype 1–∞ occurrences of 

<rng:ref name="data.pointer"/>
separated by whitespace

These elements may appear anywhere within the elements lem and rdg, and also within any of their constituent elements.