[Koha-devel] MARC::Record, record length and leader

[Robin Sheat]

Op 11-04-12 23:12, Ian Walls schreef:
> Is the record length portion of the leader really useful to anyone
> anymore?  It's really a much more valuable concept 30 years ago, when
> storage in bytes was a real consideration.

It's not really for that, it's to allow seeking through records on tape
to be efficient (at least, the way it's designed suggests that to me.)
This also shouldn't be a consideration in this day and age.

> I'd say just stop counting at 99999, and let the export scripts provide
> the recalculation, truncation or warning.  Since we don't include items
> internally in our MARC except for indexing, we shouldn't run into this
> situation very often now.

This would be OK for a single record. My concern is if we ever end up
with a block of USMARC records glommed together, could we separate them
out without a correct length header? Is there an "end of record" flag?

> Novel idea:  what about allowing hexidecimal values for those 5
> characters?  That'd give us an extra 948577 bytes, which would cover
> most cases, I'd think.

I think that's a bandaid on top of something that needs a real solution,
like avoiding USMARC. Technically the length part in MARCXML is
unnecessary, I expect that it is just there so that you can simply and
procedurally convert between the two formats.

Also, it'll create a terrible nightmare when interacting with other
systems that get upset by incorrect length headers. I think we'd be
better off failing in a graceful manner/working around by setting to
99999, and avoiding the use of USMARC as much as possible. Maybe we
could then move a step past that and avoid the use of MARC entirely ;) I
heard RDA was the new hotness...

Robin.

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