https://learn.microsoft.com/zh-cn/dotnet/api/system.windows.automation.textpattern.underlinestyleattribute?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
TextPattern.UnderlineStyleAttribute Field (System.Windows.Automation) | Microsoft Learn
Identifies the UnderlineStyle (TextDecorationLineStyle) attribute of a text range.
field systemtextpatternwindowsautomationmicrosoft