Metadata can be associated with each layer in a GDB database. Metadata is a set of string name and value pairs. Foe example, if the NO_DATA_VALUE metadata field for raster channels is provided, the name or tag is NO_DATA_VALUE and the value is treated as a special raster image value, which is a no-data or missing data value.

Metadata associates pointers to related topological vector layers and indicate display information (such as preferred scaling, LUTs, and PCTs) with raster layers. These include a special class of layer reference metadata tags. Any tag that ends in _REF is treated in the layer reference format. A layer reference is a special format for referring to other layers in the same or different GDB databases.

Caution: Although there are a variety of predefined metadata tags with special meanings, there is no system-imposed restriction on what metadata tags can be used. In essence, metadata associates application-defined or translator-defined information with data layers without requiring that the whole GDB system or all GDB applications be aware of issues relating to that metadata.

For more information about specific metadata used with these GDB layer types, see the raster and vector sections.

© PCI Geomatics Enterprises, Inc.®, 2024. All rights reserved.