Hi Arun,
No, that is not correct. I think you might be confusing the "<optional_parameters>" in the documentation (which are for formatting: dpi, orientation, scaling etc) with parameters in the report.
To refresh with a parameter value and export, your steps would be as follows:
(I'm assuming "Choose Language" is your prompt question and "EN" is the answer
1. Refresh with new value
PUT (Accept: application/xml) .../documents/<docID>/parameters
body:
<parameters>
<parameter>
<id>0<id> <-- assuming this is the correct ID
<name>Choose Language</name> <-- assuming this is the param name (tag not req'd)
<answer>
<values>
<value>EN</value>
<values>
</answer>
</parameter>
</parameters>
2. Export to PDF
GET (Accept: application/pdf) .../documents/<docID>
Dan