Metadata
One of the key stages in GIS development is the creation of metadata that describes thematic layers. The primary purpose of the metadata is to provide general information about a layer, its purpose, and its content. A standardized, unified template has been developed, according to which all layers and supplementary data are described. For each layer, regardless of its content, a single metadata file is created. These metadata files are simple text files in the XML (eXtensible Markup Language) format.
Each XML file contains the layer name and the type of data it represents. A significant part of the description is information on the map projection and the scale or resolution of the data representation. Additionally, the geographic region to which the layer data covers is specified. Mandatory elements of the metadata include full citation details for the layer, including authors, year of creation, and data source. The metadata also indicate the time period during which the data were collected or the publication year of the source on which the layer is based.
Each metadata file includes a brief description of the layer. This may contain additional characteristics, information about the layer creation methodology, and recommendations for data usage and visualization. This is the most important and informative component of the layer description.
A separate section of the metadata file lists, explains, and briefly describes the fields of the layer’s attribute table, which represent specific parameters (attributes). In some cases, individual parameters may take coded values. In such cases, all possible values for each parameter are listed and explained.
All metadata are stored in file-based database. Access to the metadata allows users to gain detailed information on the GIS content, the quality and detail of the provided data, and to make informed decisions regarding the access to specific data layers.