January 27, 2021
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SALT (Part II): Elements of SALT

  • By Hitesh Seth
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In the second part of our "SALT" series we will endeavor to understand the syntax of the key SALT elements and their usage.


The <prompt> element is the main element for speech-output. It allows SALT-based applications to play prompts using TTS (Text to Speech Synthesis) or pre-recorded audio prompts. The SALT 1.0 Specification requires SALT Browsers to support W3C SSML (Speech Synthesis Markup Language), however other TTS markup languages may be supported as well.

    <prompt id="" bargein="" prefetch="" xmlns="" xml:lang="">
        --- content of the prompt ---

Prompts are queued and played back by the SALT Applicaiton using the prompt_id.Queue() and prompt_id.Start() methods.


  1. Simple TTS Prompt:
    <prompt id="Welcome">
    Welcome to your SALT application. What would you like to do today?
  2. Pre-recorded Audio:
    <prompt id="RecordedPrompt">
        <content href="welcome.wav"/>
  3. Prompt using external SSML (Speech Synthesis Markup Language) Content:
    <prompt id="ExternalContent">
         <content href="Welcome.ssml" type="application/ssml+xml"/>
  4. Dynamic Prompt:
    <prompt id="DynamicPrompt">
        Did you say <value targetelement="txtOption" targetattribute="value"/>?


The <grammar> element is used within <listen> elements (described later) for specifying input grammars. A speech grammar specifies a set of utterances that a user may speak to perform an action. SALT Browsers are required to support an XML form of W3C SRGS (Speech Recognition Grammar Specification). Additionally, other grammar formats may be also supported as well.

    <grammar name="" src="" type="" xmlns="" xml:lang="">
        --- content of grammar (when inline grammar is used ---


  1. Using Inline Grammars:
    <grammar xmlns="http://www.w3.org/2001/06/grammar">
            --- line grammar in SRGS format ---
  2. Using external Grammars
    <grammar src="Employees.grxml" type="application/srgs+xml"/>

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This article was originally published on October 1, 2002

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