Documentation for <script LANGUAGE=Windchill>

I am using Windchill PDMLink Release 13.0 and Datecode with CPS 13.0.2.0

We request to share documentation for <SCRIPT LANGUAGE="Windchill">

Here are the errors that I faced
We have a requirement to add EC number, EC Name and Priority to any Email sent out based on EC in Email Subject Header.
We plan to modify below email templates to include the required details.
../Windchill/codebase/templates/workNotification
1.GeneralSubject.html
2.GeneralSubject_en_GB.html
3.GeneralSubject_en_US.html

We want to add a condition to include the workflow variables to add above mentioned details only when the workflow context object/primary business Object is of type WTChangeOrder2 . We added variable with below code , it works fine. The required details are added in the email Subject.

<SCRIPT LANGUAGE=Windchill> <!-- beginSubject --> </SCRIPT>

<SCRIPT LANGUAGE=Windchill> <!-- addText text="EC " --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- getProcessVariable varName="pboECNumber" --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- addText text=" - " --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- getProcessVariable varName="pboECName" --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- addText text=" (" --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- getProcessVariable varName="pboPriority" --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- addText text="): " --> </SCRIPT>
<SCRIPT LANGUAGE=Windchill> <!-- getActivityName --> </SCRIPT>

<SCRIPT LANGUAGE=Windchill> <!-- endSubject --> </SCRIPT>

We tried to add if condition with below check

<SCRIPT LANGUAGE="Windchill"> <!-- contains substring="WTChangeOrder2" --> </SCRIPT>

Also tried below

<SCRIPT LANGUAGE="Windchill"> <!-- contains variable="pboType" substring="WTChangeOrder2" --> </SCRIPT>

But this throws an exception.

Could you help us understand the <SCRIPT LANGUAGE="Windchill"> API/handle conditional check ? Is there any documentation for this ?