: Abbreviation for Chopin's Piano Sonata No. 2 in B-flat minor, Op. 35 (famous for its "Funeral March").
: Likely a specific catalog number or internal archival ID (possibly related to the Philips or Deutsche Grammophon labels, which often use 5-digit sequences). ChSon2_30038Per-EAC_FLAC.rar
The "write-up" included in such archives typically includes: : Abbreviation for Chopin's Piano Sonata No