How are ant % parameters in DITA OT cmd files resolved?

SDL uses .cmd files at the root of the DITA OT which use % definitions. Our custom plugin defines a  -Dakamai.brandname=%8 parameter based on a custom SDL metadata field.  Our ReqMetaDataExportForPublicationXMLForPubObject.xml has been updated to get this metadata.

Where can I see what "%8" parameter is resolving to?  I don't see anything in the .log in the output.   I can't figure out how the connection is being made between the SDL metadata and the ant parameter being defined. 

The cmd file for our custom webhelp format contains this: 

@ECHO OFF
CALL config.cmd
@ECHO OFF
CALL config.custom.cmd
@ECHO OFF

PUSHD %PS_DITAOT%

CALL dita-ot-build.cmd

ECHO ********************************************************************************
ECHO GENERATING REQUESTED OUTPUT USING DITA OPEN TOOLKIT
ECHO ********************************************************************************

REM "%JAVA_HOME%\bin\java" -jar lib/dost.jar /id:"%1" /tempdir:"%1/temp" /i:"%1/%2" /outdir:"%3" /draft:"%5" /filter:"%1\context.ditaval" /copycss:yes /transtype:"%4" /cleantemp:"%6" /validate:"%7"

REM -Ddita.input.valfile=%1\context.ditaval
"ant" -Dtranstype=%4 -Dargs.input=%1/%2 -Doutput.dir=%3 -Ddita.temp.dir=%1/temp -Dargs.draft=%5 -Dclean.temp=%6 -Dvalidate=%7 -Dargs.logdir=%3 -Dakamai.brandname=%8 -logfile %3/%2_%4.log


ECHO ********************************************************************************
POPD
ECHO ON
EXIT

Our custom plugin's build file uses this in a property:

<property name="akamai.brandname" value="${akamai.brandname}" />
<condition property="isATTBrand">
<equals arg1="${akamai.brandname}" arg2="att"/>
</condition>

And then executes the targets based on the property value, using if/unless:

  <target name="akamai-headerfooter-akamai" unless="isATTBrand" >

....

  <target name="akamai-headerfooter-akamai" if="isATTBrand" >

....