Hi Steven,
The comparison tool uses the marc2bibframe2 stylesheet. In marc2bibframe2 the bf:unit/bf:Unit property/class pair aren't used anywhere, which means they aren't in the conversion specifications.
Digging deeper, I checked the 3xx fields mapping<http://www.loc.gov/bibframe/mtbf/ConvSpec-3XX-R1p.xlsx> and the NumericSubfields<http://www.loc.gov/bibframe/mtbf/ConvSpec-NumericSubfields-R1p.docx> conversion specifications. There is an example of bf:unit in 300 – Physical Description in the NumericSubfields document which moves 300$f into a rdfs:label in a bnode connected to bf:unit (w/o the type 'a bf:Unit'; a typo). The 3xx field mappings put $f in a string in the Extent as a display label and don't specify the use of bf:unit/bf:Unit.
Here's the example from the NumericSubfields document w/the types added (also missing a bflc:AppliesTo) and a rdfs:label ("Make a string of all a, f, g and including all repeats of subfields. Keep in order as in field, insert blank for each subfield code then put this string in rdfs:label").
300 ##$3poems$a1$fpage ;$c108 cm. x 34.5 cm
<instance> bf:extent [ a bf:Extent ;
rdfs:label "poems 1 page ; c108 cm. x 34.5 cm";
rdf:value "1" ;
bf:unit [ a bf:Unit;
rdfs:label "page" ] ;
bf:dimensions "108 cm. x 34.5 cm" ;
bflc:appliesTo [ a bflc:AppliesTo;
rdfs:label "poems" ]].
My guess is you also could use this with the contents of $a when you determined somehow it contained a number and a unit (not the hardest regex in the world to write...):
300 ##$a95 linear ft.
<instance> bf:extent [ a bf:Extent ;
rdfs:label "95 linear ft.";
rdf:value "95";
bf:unit [ a bf:Unit;
rdfs:label "linear feet"]].
As you mentioned, the pair are not used in the editing profiles for Bf 2.0. I don't think we've had anyone ask us to split out the value from the units, but we could implement the second example pretty easily.
Kirk Hess
Library of Congress
From: Bibliographic Framework Transition Initiative Forum [mailto:[log in to unmask]] On Behalf Of Steven Michael Folsom
Sent: Wednesday, November 08, 2017 4:09 PM
To: [log in to unmask]
Subject: [BIBFRAME] bf:unit/bf:Unit and bf:extent/bf:Extent
A quick question I’m hoping LC can clear up…
Can you give an example of how bf:unit/bf:Unit are supposed to be used with bf:extent/bf:Extent? I tried using the BF comparison tool haven’t found an example of bf:unit/bf:Unit being used. I also found no mention of bf:unit/bf:Unit in any of the bfe profiles.
--
Steven Folsom
Metadata Specialist
Cornell University Library
http://orcid.org/0000-0003-3427-5769
http://vivo.cornell.edu/individual/sf433
@sf433
