EMF Measurements Database, an EMF RAPID Program Engineering Project Last updated: June 24, 1997

Metadata Specification

This document provides a formal description of metadata structure and content for the EMF Measurements Database.

The purpose of the metadata is to describe the data associated with a data set in the Database. The metadata performs two basic functions in the Database: 1) to inform a potential user what a data set contains; and 2) to document the structure and interpretation of the data products for the user.

Reading the Specification

The metadata specification is composed of a list of elements. The elements form a tree structure. There are two types of elements: 1) branch elements which provide structure; and 2) leaf elements provide the content of the metadata. At the root of the metadata tree is a branch element called `metadata'. The metadata element is composed of three other elements (dataset description, data model and data products), each of which is also a branch element composed of other elements.

Each element is assigned a reference number to help the reader in navigating the specification. The element definitions are listed in order by reference number in the body of the specification. A list of elements sorted alphabetically is presented at the end of the specification to help locate the element by name.

Each element definition includes the reference number, the element name, a discussion of the element and what it represents, a formal content model specification, and a list of parent elements (branch elements where the current element can occur). Elements in the content model and parent specifications include the associated reference number as a subscript.

The content model of a leaf element is given as `Free Text'. This indicates that the element contains textual information about the data set.

The content model of a branch element is more complex. Branch elements do not contain textual information directly, but rather contain other elements. Those elements may be themselves branch elements or leaf elements. Keywords are used to indicate how the constituent elements are composed. A keyword always comes immediately after an opening parenthesis and applies to all the elements until the matching right parenthesis. In the content model for the root element `metadata', the keyword `sequence' is used. Therefore, `metadata' is composed of the sequence of elements `dataset-description', `data-model', and `data-products'). Other keywords include `exclusive-or', `zero-or-one', `zero-or-more', and `one-or-more'.

The Specification

Alphabetic Listing of Metadata Elements