Tag Group Definitions (TagGroupInfoList)

Although not required, a tag dictionary may contain tag groups. The Tag Group Definitions folder in a TagDictionary property sheet contains the collection of TagGroups for that dictionary. A tag group provides a structure that lets you add multiple tags to an object with a single action. Typically, tags are in a group because it is common for each of the tags to be assigned to a single component.

For example, in the Haystack Tag Dictionary, there is a tag group for “discharge air temp sensor” that contains the following set of individual tags:

discharge
air
temp
sensor

Once a tag group is applied to an object, it implies all of the individual tags in its tag list, as well as implying a marker tag that bears the name of the tag group. This allows you to easily define a NEQL search for the marker tag for that tag group rather than defining a search by concatenating each of the tags in the tag group’s tag list.

The Device Manager and Point Manager views of a driver, and the Edit Tags dialog are the primary methods for adding a Tag Group to a component.

Note: When creating or editing a tag group, include only those tags that have a corresponding tag definition in the parent tag dictionary. One way to guarantee it is to populate the tag group’s tag list with tags copied only from the tag definitions list in the tag dictionary.

TagGroup properties

When using the Edit Tags dialog to add a tag group, the tag group displays in the Direct Tags tab as an Ord to the tag group itself, and once the change is saved the individual tags of the tag group display in the Implied Tags tab.

A tag group can contain tags from other tag dictionaries. You can add a tag to a tag group that overrides the namespace of the parent tag dictionary. This allows you to define a tag group that contains tags from multiple tag dictionaries.

Note: There is no verification that a tag name entered in the Add Tag dialog box is actually defined in a tag dictionary. If the tag definition does not exist, the added tag is an ad hoc tag. It is possible to use ad hoc tags, although a tagging best practice is to include only those tags that have a corresponding tag definition in the parent tag dictionary.

You can add a single “Data Policy” to a Tag Group Definitions folder (or to a Tag Definitions folder). A data policy provides additional metadata that can be associated with a tagged component. For more details see “Data Policies”.

Type	Value	Description
Validity		Specifies criteria to be met in order for this tag group to be applied to an object.
TagInfoList		Contains the collection of tags that make up this tag group.