<!-- The list of the names of referensed projects -->
<?define ACAD_VERSIONS=R172;R182;R190?>
<?foreach ACAD in ACAD_VERSIONS?>
<Feature Id="Feature.$(var.ACAD)" Title="$(var.ACAD)" Level="1">
<Component Id="cmp$(var.ACAD)" Guid="*" Directory="INSTALLFOLDER">
<File Id="extension.$(var.ACAD).dll" Source="$(var.$(var.ACAD).TargetPath)" KeyPath="yes"/>
</Component>
...
</Feature>
<?endforeach?>