Q:
In a PDF form, I’d like for a check mark to appear instead of an ‘X’. How can I change this?
A:
The “interactive forms” code sample shows how to change whether a check mark, cross, etc. is used the in the check box:
https://www.pdftron.com/pdfnet/samplecode.html#InteractiveForms
See the “createCheckmarkAppearance” function for details.