SDI Convergence - Nederlandse Commissie voor Geodesie - KNAW

data and grid computing infrastructures with associated metadata to deliver on-line
spatial data processing and modelling.
Figure 1 organizes metadata into several simple functional classes and assists in illustrating
the conceptual relationships between spatial data, spatial data metadata and the
different forms of model metadata.
Figure 1: Functional classes of metadata.
This approach to describing metadata is slightly unorthodox because it extends the
common paradigm that uses metadata largely for purposes of search and discovery.
The term metadata, purportedly first used in 1969 (Howe, 1996) is defined as “structured
information that describes, explains, locates or otherwise makes it easier to retrieve,
use or manage an information resource” (NISO, 2004). A more commonly used
definition is that metadata is “data about data”. Here we use ‘model metadata’ as a
term or descriptor meaning ‘data about models’. This is not to be confused with the
terms meta-modelling and meta-models as these describe a contemporary approach to
model selection, construction and assembly (Keller and Dungen, 1999; Bridewell et al.,
2006).
The NISO (2004) metadata report states “Metadata is key to ensuring that resources
will survive and continue to be accessible into the future”. In Agriculture and Natural
Resource Management (NRM) this is undoubtedly true for metadata about data and
information resources as these are often primary sources of knowledge describing the
state and nature of environmental systems and are important for comparative analysis
regardless of their age. However, this is probably less so for model metadata as models
represent the interpolative, inferential or processing systems that are used in research.
These methodologies are generally subject to continual improvement and consequently
it could be argued that model metadata has a greater potential to age and is
most useful when it is more current. Although there are metadata standards for data
and information (ISO 19115) similar standards are only beginning to emerge for model
metadata.
The functional levels shown in Figure 1 are closely related to three main types of metadata:
descriptive metadata, structural metadata and administrative metadata (NISO
2004). At level 1 the metadata is primarily used as a resource for discovery and identi-
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