The LTER EML Unit Registry Project

In development, July 2005

Motivation & Process

Well specified units are at the heart of measurement comparability. Today's data integration efforts are highlighting a range of unaddressed and unresolved unit definition issues involving syntactic and semantic ambiguities and conflicts. The community repository or "unit registry" presented here addresses some of these issues by sharing unit names, types, definitions, and forms while introducing the concept of site-working group-community-domain scope. The initial goals for our design team were three-fold: 1) preparation of a prototype application to enhance discussion at a Dictionary Working Group at the August 2005 LTER Information Manager meeting, 2) establishment of a community process that engages and benefits participants, and 3) development of a dictionary process that captures the migration of units through multiple levels. This prototype represents an LTER site-network collaborative design effort to meet community needs by creating a mechanism for locating units compliant with the EML standard, for bringing together local solutions, and for prompting cross-site discussion of units.

Products

The application currently provides a table listing of units and a search of the unit registry; there are plans for unit submissions. The registry currently includes "standard units" defined in EML v2.0.1, and "custom units" created by several sites (PAL, SBC, GCE, FCE, CCE). It is intended to support EML creators by providing for:

• listings of the standard units currently supported by EML
• submission of a local site's custom units to a community collection
• access to XML code fragments for existing custom units defined by another site
• establishment of a site-network design team to develop common language for support of EML enactment and site work practices
• establishment of a dictionary process for unit migration through multiple levels: site, working group, community, and domain or EML scope
• Design of the "LTER Custom Unit Registry" relational database schema

Notes

• Searches support substring expressions
• Unit names are of the form "molesPerLiter"
• Only SI units require an associated Unit Type
• Unit Type names are hyperlinked to list related Units

Design Team