<sub> tags suggest substitute text to the TTS engine. This tag is only available with the Cepstral Theta TTS engine.
Substitutes the enclosed text with the value of the attribute.
<?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.