Introduction to Attributes
This section describes each attribute used in the Tag Set in alphabetical order of their tag names (i.e., attribute type names). The tag name is the shorter machine-readable name used in tagged documents, XML vocabularies, and by software; for example, the tag name “@id” is used for the attribute named “Document Internal Identifier”.
Each attribute is described by a separate page, where the heading for the page displays the attribute’s tag name followed by its longer descriptive name. The rest of the attribute description page discusses aspects of the attribute, its usage, and the elements to which it can be attached. The sections within the page always appear in the following order, although any given attribute description may not contain all the sections:
Contains a narrative description of the attribute. This is not a formal dictionary definition, but more an explanation of what the attribute means, what type of information it provides, or how it can be used.
Discusses expected uses for the attribute, such as when or why it might be used or how to determine its value.
Provides additional information about the attribute, such as similar or contrasting attributes, processing information, or material about the base element.
Used on Elements:
Performs three functions:
Elements — The elements that may take the attribute are named following the phrase “Used on Elements:”.
If the attribute can be used in more than one way, or with several slightly different meanings, there will be more than one “Used on Elements:” section. Each “Used on Elements:” section is followed by a value table that describes the attribute’s values when it is used with the elements just listed. For example, the attribute may have exactly the same meaning whenever it is used, but sometimes it is required while other times it is optional, so there will be two “Used on Elements:” sections, one naming all the elements for which the attribute is required, and one naming all the elements for which the attribute is optional.
Value and Meaning — Following each “Used on Elements:” section is an Attribute Value Table that lists the possible values of the attribute and explains selected values. When the attribute originates in the TBX Tag Set, the Attribute Value Table also explains the meaning of each value. Attributes defined in the NISO STS Tag Set do not have their values explained; instead, users are referred to the appropriate page in the NISO STS Tag Library to learn more about the attribute.
The Attribute Value Table typically contains two columns, although a third column titled “Behavior” may be present. Each row in the table describes one value, where:
Restriction — The last row of the table contains either the word “Restriction” or the words “Default value”. “Restriction” indicates whether the attribute must be supplied when the relevant element is used, or the attribute is optional and may be given on the element. “Default value” indicates the value of the attribute that will be used (by systems that read the schema) when the document does not supply a value.
Suggested usage — For those attributes whose value is defined as text (letters, numbers, or special characters), this Tag Set does not enforce any particular value(s), but a list of suggested values may be provided.
Provides an excerpt of a tagged XML document, showing use of the current attribute. An attribute is shown in the context of one of its elements, with the current attribute highlighted.