Thanks for that walk-through explanation. I probably get it even. I should have followed the reference for the definition of eol in Section 3 of RFC 7468. It was only one more human stack call. I appreciate the clarification on the valid text encoding of explanatory text and of the header and footer lines (the not safe base64 stuff with is obvious enough). I will endeavor to send on wire with <CR><LF> but not expect that to come back. For all I know, Python will do or already does that for me. I'll have to figure that out.