Matt, the photo shows a ‘standard’ BAe published speed-card book for an Avro RJ 100.
AFAIK these were never aircraft specific, instead they related to the performance section of the flight manual (AFM), which more normally was associated with operators, but not uniquely.
OSH 256 is more likely to have been a tech pubs reference, but still could (confusingly) reference a particular aircraft. Crossair in particular, as some or all ? of their RJ100 aircraft were modified to enable flap 30/33 take off, but the card shown does not indicate that.
Re 256, aircraft E2256 was a RJ 85 D-AVRA operated by LH City Line.
The AFM always related to a specific aircraft via mod number pages, and thence the manufacturers build number. A BAe aircraft reference would have been E3291 (HB-IXH). I forget what E was, but ‘3’ relates to a series 300 ‘146’, but ‘291’ was a RJ100. All RJs were certificated under the 146 title; confusing, but it made sense to BAe and UK CAA.
Conclusion; RJ 100, pre flap mods, build number unknown, but max weight on the card may provide a clue.