NSDI_L Re:GILS versus FGDC

[Kate Ord <kateo@erin.gov.au>]

Happy New Year to all my fellow metadata enthusiasts. 

Further to the last email which I sent out to the list on 
GILS - the Global Information Locator Service, I spotted 
this on the U.S. NSDI list. I thought it was 
an interesting summary of some of the debate in the USA on 
core versus full metadata and how GILS and FGDC fit together.
It also includes a URL for an internet metadata entry form for the 
minimum mandatory FGDC elements.

I am looking forward to hearing from other members of the list 
about their ideas on metadata and its implementation.

Cheers,

Kate

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>From mail@fgdc.er.usgs.GOV Tue Dec 24 16:41 EST 1996
Date: Mon, 23 Dec 1996 09:47:46 +0000
From: Doug Nebert <ddnebert@usgs.gov>
Organization: Federal Geographic Data Committee
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Subject: NSDI_L Re:GILS versus FGDC
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Potter at Island Resources Foundation wrote:
> 
> Could someone briefly explain the relationship of this worldwide Global
> Locator stuff to the "biological" geo-spatial metadata that the Virgin
> Islands Biological Information Node is getting ready to mount in a FGDC
> Clearinghouse?
> 
> Based on the pilot data that USGS has displayed in the ENRM site in Europe
> (URL in press release below), it looks as though we (i.e., agencies in the
> Virgin Islands) are spending a lot of time documenting data that is not
> necessary to do a reasonably competent search of environmental information
> for the Virgin Islands.
> 
> Especially in places like the Eastern Caribbean--and other developing
> areas--where ALL resources are in desperately short supply, I think I would
> like to fill out a GILS source record rather than laboring over
> FGDC-compliant records with a couple hundred elements.
> 

The FGDC Metadata Standard has a large number of fields so that
specific, and potentially searchable, information could be stored and
processed in the future. Perhaps, due of its complexity, it also goes
unrecognized that it supports a high degree of optionality in the
preparation of still-compliant FGDC metadata. 

There are really two roles for metadata that one needs to address before
beginning to document data:

1. Documentation of content and history. The FGDC metadata standard can
support a very large amount of historical and contextual information so
that it is not lost in a "Supplemental Information" block. This ensures
that a data set is properly documented for current and future users so
that the strengths and weaknesses of the data are known. If one has this
level of metadata and the raw data set itself, there should be adequate
information for translation and appropriate use to be made of the data
set.

2. Brief documentation for discovery.  This is the catalogue or "search"
support role we have for metadata.  Almost all catalogs are of this
model, providing enough information to, hopefully, find the data but
ususally not enough information to do anything meaningful with the data
once it is downloaded. If one has this level of metadata, its location
and basic characteristics are known -- like a card catalog entry.

Roles one and two are complementary.  If one has the detailed metadata,
support of search comes with no extra effort.  Of course, the reverse is
not true -- one can never synthesize a detailed metadata record from a
basic GILS or FGDC metadata record. It is important to review your
requirements -- if the goal is only to support discovery but not to
document the data, then the development of brief records may be
warranted. If you need to track the basic quality of information so that
the data are used advisedly, then a fuller record may be warranted.

I think there is adequate middle ground here -- even within the context
of the FGDC Metadata Standard. A minimally-compliant FGDC metadata
record can contain less than 30 valued elements, if one fills in only
the mandatories. Such a record may be just enough for discovery but fall
short of adequate documentation. So the project can decide how many more
elements to support to make a "basic" record, and at the same time be
also compliant with the FGDC metadata standard.

GILS records are designed solely for discovery -- to locate a documented
data resource somewhere. Unlike FGDC metadata, they do not have more
depth to store detailed information. The FGDC (GEO) and GILS profiles
support some of the same search fields, called Use Attributes, quite
intentionally, allowing a GEO server to also be searched as if it were a
GILS server, providing a larger set of servers to search.  One notable
departure is that the geographic coordinates, although supported as
presentable fields, are not uniformly populated or made searchable via
GILS servers; in other words, one cannot reliably search GILS for
spatial data based on coordinates, which is a central requirement of
FGDC.  So in summary, FGDC records *do* make adequate GILS records, but
the reverse is not true.  But we are feeding the broader world of
locator services by being "like" GILS.

> 
> If I accept the guidance provided by the trainees, would it really make
> more sense to do something simple like make "a lot of GILS-compliant
> records," rather than "a few FGDC-compliant records?"
> 

My guidance would be to research the minimum set of metadata elements
that are mandatory for an FGDC record and add those few extras you deem
necessary for your community to provide minimum documentation. You can
always fill in more metadata for some datasets, but it may not be
necessary (or available) for many of them. 

If you'd like to review a Web-based form to enter metadata close to the
minimum set (by my interpretation), check out
URL:http://www.fgdc.gov/clearinghouse/metalite.html . I am connecting
this to a perl cgi-script to collect these basic metadata entries and
feed them to the Isite indexer, so one can collect basic records via the
Net from any forms-capable browser and have them served as FGDC metadata
the same day. Stay tuned...

Doug Nebert
FGDC Clearinghouse


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