Using SI with one-of in SRGS?

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I have a question on using Semantic Interpretation for
Speech Recognition with SRGS one-of elements:

I am working on a speech recognition extension for the Firefox
browser, and to test my understanding have put together a grammar
for numbers, e.g.

  <rule id="units">
  <one-of>
  <item>one</item>
  <item>two</item>
  <item>three</item>
  <item>four</item>
  <item>five</item>
  <item>six</item>
  <item>seven</item>
  <item>eight</item>
  <item>nine</item>
   </one-of>
  </rule>

  <rule id="tens">
  <one-of>
  <item>twenty</item>
  <item>thirty</item>
  <item>forty</item>
  <item>fifty</item>
  <item>sixty</item>
  <item>seventy</item>
  <item>eighty</item>
  <item>ninety</item>
  </one-of>
  <item repeat="0-1"><ruleref uri="#units"/></item>
  </rule>

for utterances like "twenty one", and similarly for more
complex numbers.

I now want to use SI tags to compute the numerical value as
the interpretation. I started by adding tag elements for
the numeric literals, e.g.

  <rule id="tens">
  <tag>var $units=0;</tag>
  <one-of>
  <item><token>twenty</token><tag>20</tag></item>
  <item><token>thirty</token><tag>30</tag></item>
  <item><token>forty</token><tag>40</tag></item>
  <item><token>fifty</token><tag>50</tag></item>
  <item><token>sixty</token><tag>60</tag></item>
  <item><token>seventy</token><tag>70</tag></item>
  <item><token>eighty</token><tag>80</tag></item>
  <item><token>ninety</token><tag>90</tag></item>
  </one-of>
  <item repeat="0-1"><ruleref uri="#units"/></item>
  <!-- the following won't work as needed -->
  <tag>out = $tens + $units</tag>
  </rule>

where the declaration of $units in the first tag element is based
upon an example in the SISR specification from section 3.3.2.

Unfortunately, I don't know how to reference the value obtained
from  the one-of element within the "tens" rule and $tens clearly
won't work as written in the above example.

So how do you name the value from an item or from a one-of
within a rule without breaking it out into a separate rule?

Many thanks,
- --
  Dave Raggett <dsr@w3.org>  W3C lead for multimodal interaction
  http://www.w3.org/People/Raggett +44 1225 866240 (or 867351)

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Received on Tuesday, 12 April 2005 10:02:51 UTC