Hi,
Thank you for interest in Syncfusion products.
yes, DocIO is an Non UI control. User can generate the document programmatically in .Net without any user interaction. It is a .NET library that can read and write Microsoft Word files. It features a full-fledged object model similar to the Microsoft Office automation libraries. Essential DocIO makes it easy to create rich Word documents from your applications.
And user create new document or edit the existing document through programmatically. The user can change the format of the text or anything. But we don't have any API's to set the ruler of the document.
Please go through our Online documentation and also our feature page to know about the available features in DocIO:
http://help.syncfusion.com/ug_64/DocIO/FeatureAndBenefits.htmlPlease let me know if you need any further details.
Best Regards,
Bhuvana