# \<sub>

## \<sub> <a href="#sub" id="sub"></a>

`<sub>` tags suggest substitute text to the TTS engine. This tag is only available with the Cepstral Theta TTS engine.

### Attributes

<table><thead><tr><th width="133.33333333333331">Name</th><th width="166">Data type<select><option value="a4b46b0bcde745c195360c57600e432f" label="String" color="blue"></option><option value="3150ce0d433644f8b57c65660f482874" label="Integer" color="blue"></option><option value="20d77c0a5a7f4e78994da30238687a88" label="Boolean" color="blue"></option></select></th><th>Description</th></tr></thead><tbody><tr><td>alias</td><td><span data-option="a4b46b0bcde745c195360c57600e432f">String</span></td><td>Substitutes the enclosed text with the specified value.</td></tr></tbody></table>

### Notes

None

### Example

```markup
<?xml version="1.0" encoding="latin-1"?>
<vxml version="2.0">
  <form>
    <block>
      <prompt>
        This dialog is being processed by
        <sub alias="Plum DEV">
          plum D E V
        </sub>
      </prompt>
    </block>
  </form>
</vxml>
```

The output of the above script would be:

> Computer: This dialog is being processed by Plum DEV.

### Child Tags

None

### Parent Tags

[\<audio>](https://docs.plumvoice.com/dev/voicexml/tags/audio-tag), [\<emphasis>](https://docs.plumvoice.com/dev/voicexml/tags/emphasis-tag), [\<enumerate>](https://docs.plumvoice.com/dev/voicexml/tags/enumerate-tag), [\<foreach>](https://docs.plumvoice.com/dev/voicexml/tags/foreach-tag), [\<paragraph>](https://docs.plumvoice.com/dev/voicexml/tags/paragraph-tag), [\<prompt>](https://docs.plumvoice.com/dev/voicexml/tags/prompt-tag), [\<prosody>](https://docs.plumvoice.com/dev/voicexml/tags/prosody-tag), [\<sentence>](https://docs.plumvoice.com/dev/voicexml/tags/sentence-tag), [\<speak>](https://docs.plumvoice.com/dev/voicexml/tags/speak-tag), [\<voice>](https://docs.plumvoice.com/dev/voicexml/tags/voice-tag)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.plumvoice.com/dev/voicexml/tags/sub-tag.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.