whether <code>inclUncertain=TRUE</code> or
<code>inclUncertain=FALSE</code>) from the output set, when they are identified as
positive control animals - i.e they are associated with a TX parameter
'TCNTRL' containing a word from this set of words:</p><ul><li><p>['positive','reference']</p></li>
</ul><p>The age in days at reference start date is calculated for each animal based
on the age related variables in DM:</p><ol><li><p>If BRTHDTC is populated compute DM.RFSTDTC – DM.BRTHDTC + 1</p></li>
<li><