## 4 Expansion of previous work
### Dataset derived metadata - geometry  
Deriving metadata from data geometry is conventionally limited to the calculation and update of projection-dependent bounding coordinates of the entire dataset. Typically employed to provide a rudimentary spatial component for searching indexed metadata catalogues, such coordinates do not however convey extent information that is easily interpreted by end-users. Boundary names (e.g. political, administrative regions) provide more user-friendly extent attribution but as these are not directly coupled with the spatial component of the dataset, any change to the data's geographic bounds will not be reflected in such attribution unless specifically detected and manually addressed. Such issues are circumvented through the association with the data a layer depicting application-relevant boundaries, enabling the automated identification of a dataset's potentially evolving extent by a process of reverse geocoding. Feature sets are programmatically overlain with such boundary reference layers, returning the name of the enveloping region. Extent identifiers within the metadata are accordingly coupled with underlying spatial data, removing the need for manual nomination and update that can be subjective and open to error. A related issue pertains to spatial resolution. The base GEMINI specification for instance outlines an _Extent_ field domain of high level areas such as England, Wales, Great Britain, British Isles, but sole inclusion of a reference boundary layer with these regions may be insufficient for applications with more fine-grained requirements, as with those of local government. Incorporating subsequent reference layers of increasing scale can facilitate improved extent identification and help relay more precise information within the resulting metadata. To illustrate, a test dataset containing the geographic distribution of the invasive Giant Hogweed species (_Heracleum mantegazzianum_) in the south of Scotland is used (Figures 3, a-c). Figure 3a depicts the problem of registering an extent of Scotland for a rather localised phenomenon found in the south east of the country. Introducing an administration \begin{table}
\begin{tabular}{|c|l|c|} \hline
**Field** & **Definition** & **Alias** \\ \hline Originating & DQ\_DataQuality\_lineage\textgreater{} LI\_Lineage.source\textgreater{} & \\ organisation & LI\_Source.sourceCitation\textgreater{} & origin \\  & CI\_Citation.CI\_ResponsibleParty.organisationName & \\ \hline Originating & DQ\_DataQuality\_lineage\textgreater{} LI\_Lineage.sourceStep\textgreater{} & \\ Capture Process & LI\_ProcessStep\_description & capture\_process \\ \hline Originating & DQ\_DataQuality\_lineage\textgreater{} LI\_Lineage.sourceStep\textgreater{} & \\ Capture Date & LI\_ProcessStep\_dateTime & capture\_date \\ \hline Precision & DQ\_DataQuality.report\textgreater{} & \\  & DQ\_Element.DQ\_PositionalAccuracy\_result & precision \\ \hline Editing & DQ\_DataQuality.lineage\textgreater{} LI\_Lineage.processStep\textgreater{} & \\ organisation & LI\_ProcessStep.processor\textgreater{} & editor \\  & CI\_ResponsibleParty.organisationName & \\ \hline Edit Date & DQ\_DataQuality.lineage\textgreater{} LI\_Lineage.processStep\textgreater{} & edit\_date \\  & LI\_ProcessStep.dateTime & \\ \hline \end{tabular}
\end{table} 
Table 3: ISO-based feature metadata schema, defined using ISO 19115 entities according to ISO 19109 guidelines (all being subclasses of MD\_Metadata.dataQualityInfo). Both organisationName entries (origin, editor) may be replaced with (or supplemented by) individualName if required by the domain of application. boundary layer provides more detail (Figure 3b), showing that the recorded extent is in fact confined to the Scottish Borders.