The MARC format (and OCLC Bib. Formats document) includes this example in 
field 344:

344 ## $a digital $b optical $g surround $h Dolby Digital 5.1 $2 rda

RDA 3.16.9.3 has this controlled list of special playback characteristics:

CCIR standard
CX encoded
dbx encoded
Dolby
Dolby-A encoded
Dolby-B encoded
Dolby-C encoded
LPCM
NAB standard

RDA also says "If none of the terms in the list is appropriate or 
sufficiently specific, use another concise term or terms to indicate the 
special playback characteristics."

I think this has come up in discussion before, but can $2 rda be used in 
the 3XX fields if a term recorded does not come from a list in RDA? 
That is, since Dolby Digital 5.1 is not on the list in 3.16.9.3, is it 
correct to include $2 in the 344?  If not correct, should one 344 be used 
with no $2, or should two 344s be used as follows:

344 ## $a digital $b optical $g surround $2 rda
344 ## $h Dolby Digital 5.1

Adam

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Adam L. Schiff
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