Semantic Grammar Tags

Tags are special grammar tokens that can contain any information you wish to put in them. They are useful for transforming output — for example, an application might accept "Yes," "Yeah," or "Yes please" but return "TRUE" regardless of which is spoken. Using tags together with Semantic Interpretation for Speech Recognition (SISR) — the standard method of embedding semantic interpretation information inside grammars — is the mechanism for mapping a specific input (or range of inputs) to a desired output.

Tags are placed inside ABNF grammars using curly braces ({ }) and in GrXML using the <tag> element. In both formats, the content inside a tag is identical.

ABNF example:

GrXML example:

Because SISR allows ECMAScript (JavaScript) code, which treats the curly brace as a reserved character, ABNF tags can also be enclosed with the three-character sequences {!{ and }!}. Both methods are equivalent, except that {!{ allows single curly braces to appear within the tag itself. GrXML does not require anything special to use curly braces within a tag.

SISR is a powerful method of embedding extra information inside tags. For a tutorial and further details, see the Introduction to Semantic Interpretation.

Declaring the Tag Format

To use SISR within an ABNF grammar, include a tag-format declaration in the grammar header:

The tag-format value must be enclosed within angle brackets.

In GrXML, it is set as an attribute of the <grammar> element:

See the list of tag formats for the acceptable formats you may declare.

Related Articles

• Introduction to Semantic Interpretation — SISR tutorial.
• Tag Format
• Applying Grammar Weights — the next step in the tutorial.