\CDB\: \CDB\Metadata\: The directory that contains the specific XML metadata files which are

56 © 2016 Open Geospatial Consortium most familiar with.

3. CDB Structure

This chapter defines the CDB data store physical structure, i.e., the name of all directories forming the CDB model hierarchy, as well as the name of all files found in the CDB model hierarchy. An important feature of the CDB Model is the fact that all CDB file names are unique and that the filename alone is sufficient to infer the path to get to the file. The CDB is composed of several datasets that usually reside in their own directory structure; however some datasets share a common structure. The following sections present the directory structures for all CDB conformant datasets.

3.1 Top Level CDB ModelStructure Description

The top-level directory structure of the CDB from the root directory is described below. All of the synthetic environment content falls in these directories: 1. \CDB\: This is the root directory of the CDB. It does not need to be “\CDB\” and can be any valid path name on any disk device or volume under the target file system it is stored on. In order for the text of this standard to remain readable, all examples referring to the root CDB path name will start with \CDB\. A CDB cannot be stored directly in the root directory of a disk device or volume. A CDB path name cannot be within another CDB or CDB version. The length of the path name leading to the CDB root directory should be small enough such that the platform file system can store all possible file path names stored within a CDB. Requirements Class 29-32 req corecdb-root-requirements Target type Data instance Dependency XML Dependency CDB file hierarchy Dependency XML Schema – Part 2 57 © 2016 Open Geospatial Consortium Requirement 29 req cor eroot-file-hierarchy All of the files stored within a CDB data store SHALL be under the root directory or within a subdirectory under the root directory Requirement 30 req cor eroot-give-path Run-time applications SHALL be given the path and device on which the CDB is stored in order to access the CDB. Requirement 31 req cor eroot-access-version The CDB standard also has provisions for the handling of multiple, incremental versioning of the CDB. To support this capability, run time applications SHALL first access a predetermined version of the CDB and all its predecessors to determine content changes to the CDB. Requirement 32 req cor eroot-version-default If no change is encountered in any of the incremental versions, the applications SHALL use the content of the active default CDB. The versioning mechanism is done at the file level. Refer to Section 3.2, CDB Configuration Management, for details on how CDB supports incremental versioning. 2. \CDB\Metadata\: The directory that contains the specific XML metadata files which are global to the CDB. The directory structure and metadata descriptions are defined in Section 3.1.1, Metadata Directory. 3. \CDB\GTModel\: This is the entry directory that contains the Geotypical Models