In some name authority records recently created by LC, I've been seeing the value "a" in the cataloging source fixed field (008/39). Sources I've found show that the value "a" was used for the National Agricultural Library, and became obsolete in 1997. Can anyone explain why this value is showing up now? Has this value been repurposed since the latest update to Marc 21 format for authority data, which was in April 2018?
The University of Michigan