## 1 Introduction  
Metadata have been key to the development of geospatial data sharing initiatives since their first emergence. From early mention of 'data registers' of spatial assets in the Chorley Report [1], through pioneering initiatives such as the Federal Geographic Data Committee's (FGDC1) National GeospatialData Clearinghouse in the US and the National Geospatial Data Framework (NGDF) in the UK, to more recent Internet services such as the _Geospatial One-Stop_, _Gigateway_ and the latter's academic counterpart _Go-Geo!_, what has become known as geospatial resource metadata has consistently assumed a central pillar around which efforts have evolved [2-7]. Predicated on the basis that textual metadata records are more widely accessible to location and retrieval techniques than the geospatial holdings they describe, such services aim to facilitate and promote data exchange by registering such data surrogates within searchable catalogues or clearinghouses. Users poll catalogue contents based on dataset properties depicted in the metadata (e.g., spatial coverage, theme, keyword); result sets inform decisions as to whether datasets should be pursued, and where they may be ultimately located. While it could be argued that the core function of metadata in driving data sharing efforts has remained largely unchanged from pioneering implementations to date, encoding strategies and the mechanisms through which metadata records communicate dataset availability have seen significant progression. Fuelled principally by a desire for interoperability, domain specific metadata strategies have made way for broader standards at regional and national levels, culminating in the recent convergence around International Organization for Standardization (ISO) conventions [8-10]. Similarly, computational frameworks used to enable geospatial resource discovery continue to witness a shift away from applications developed primarily for other disciplines, such as the library community's Z39.50 protocol [6,11,12] to more recent strategies designed specifically for the geospatial domain, in particular those based upon Open Geospatial Consortium (OGC) specifications. Sophisticated proprietary offerings in addition to those produced by the open source community have arisen, providing geo-centric solutions with the potential to empower geospatial data providers wishing to publicise their holdings while also facilitating end-user discovery [13-17]. Further a-field, technologies with the potential for enhancing geospatial data exchange continue to surface. Improved networking infrastructures, coupled with the heightened availability and plummeting costs of high-speed broadband and wireless connectivity have in turn served to streamline the access and transfer of the high data volumes often characteristic of geographic datasets [18-20]. The appearance of Geography Mark-up Language (GML) has helped alleviate many of the concerns relating to data compatibility and interoperability, providing an open dialect for data transfer not bound to specific software offerings [21-23]. Meanwhile, maturing open web portrayal techniques such as those propounded by the OGC offer scope for integration with current discovery services, allowing spatial data to be previewed prior to committing resources for procurement [24,25]. Similarly, emerging geoprocessing services such as those aligned with the OGC's Web Processing Service specification offer the potential for remote processing prior to data retrieval, maximising transfer efficiencies whilst minimising end-user software and hardware demands [26-29]. And yet, considering the role that geospatial metadata retains in facilitating the discovery and exploitation of the very data resources on which the many of the aforementioned services depend, the lack of practical efforts aimed at providing easier methods for its generation is telling.