Per https://community.canvaslms.com/t5/Instructor-Guide/What-types-of-files-can-be-previewed-in-Canvas/t... the only text file extension that is supported within canvas is .txt.  However, this isn't totally accurate, since I also know that .java (java programming source code files) will also properly preview in the docViewer.

However, I've noticed that .c and .h files (C programming source code files) wlll preview in the browser, but do not preview in the iPadOS app.  This means that I can't use my apple pencil to annotate submissions.

This specific idea request is for .c and .h to be considered preview-able text files in the iPadOS app.

(and it would be nice if the official documentation reflected reality for files like .java files -- so that they will continue to work)

Ideally, the programming team should review common programming language source code file extensions and allow all of them to be treated as text files for the purpose of the docView in SpeedGrader.  I haven't recently taught other languages, so I can't speak to which are supported and which not.