Checkmark in PDF?

[minkbear]

In Acrobat Reader X, there is a checkbox on top right conner as attatchment.

So when I add a checkmark for a Sticky Note then save pdf file.

Then I traverse all annotation as sample code. (http://www.pdftron.com/pdfnet/samplecode/AnnotationTest.sphp)

I met a text annotation which's content is "Marked set by user".

My question is:

Is there a way to get the parent's annotation of "Marked set by user" annotation?

Please advice.