On Thu, Jun 10, 2010 at 5:02 PM, Samuele Kaplun <[email protected]> wrote:
> Currently when you use xmlmarc2textmarc utility, and you export to > Aleph, a dummy leader is generated, which proved to be enough for Aleph. Ahh, I wasn't aware of that existing utility. I showed the marc output from bibformat to some librarian coder friends and they said, "huh, looks like aleph sequential" :) So Aleph doesn't care about the leader values? > I am currently not an expert on the leader subject, but to me it seems > that the leader makes sense mostly in the MARC21 binary format, and when > dealing with plain library records. And it exists in MARCXML just as a > conversion consequence. Is this correct? Proof is that Invenio can do > powerful and extremely flexible things without any need for the leader. Not an expert either. I think for Invenio it really just boils down to interoperability. I mean, saying, Software X can do incredible, amazing things with internal, non-standard format Y, isn't really a remarkable statement. > In particular if Invenio has to support the leader in MARCXML how can we > map its workflows with the rigid schema of the leader: I think sensible defaults for some values combined with a minimum of conditional logic should suffice. The first part of that may be the trickier as I'm still trying to figure out defaults myself. > Also what is the meaning of certain bytes of the leader in MARCXML: > (from <http://www.loc.gov/marc/bibliographic/bdleader.html>): > > [...] > Character Positions > 00-04 - Record length > [...] > 12-16 - Base address of data > [...] leader/05 = 'n' - the term "new" in this context is confusing but I've been told "don't overthink it" leader/06 = 'a' - "...electronic resources that are basically textual in nature" leader/07 is where i'm less confident but I *think* the logic is simply 'b' for articles, 'a' for things that are part of a collection or proceedings, and 'm' for everything else. For ADS we are currently storing our internal item-type description in the 690a (which may be incorrect) and this is how i'm determining the leader/07 leader/08 = '#' - not sure about this one leader/09 = 'a' - assuming unicode I've been looking at http://www.itsmarc.com/crs/bib1465.htm for some guidance and when I have a dumb question about something I'll ask in the #code4lib irc channel. Apparently the 008 control field (http://www.loc.gov/marc/bibliographic/bd008.html) is also important to many applications, but I haven't really explored it or determined the level of importance. > In the end, probably the best thing is still to put a fake leader like > xmlmarc2textmarc currently does, with the most neutral values. Yeah, I guess I agree, although I'm not sure what a "neutral" value would be for something like the leader/07. also it's important to get the leader/09 correct as tools like pymarc need to know how to decode. > > It is true that, on the other hand, when Invenio records have been > imported from original MARC21 or from MARCXML with a leader, Invenio > should not throw away such information. Agreed. --jay ****************************************************** Jay Luker Astrophysics Data System (ADS) [email protected] Center for Astrophysics 617-495-4588 60 Garden Street MS 67 617-495-7356 fax Cambridge, MA 02138 ******************************************************
