Question around PR_RENDERING_POSITION in plain text emails

[tmyroadctfig]

What is the expected behaviour when PR_RENDERING_POSITION is set, but there is nothing set for PR_ATTACH_RENDERING? If the attachment is an image file, then Outlook seems to render the attachment as an attached file rather than an inline image.

I'm referring to the docs here:
https://github.com/MicrosoftDocs/office-developer-client-docs/blob/master/docs/outlook/mapi/rendering-an-attachment-in-plain-text.md

Thanks