It wasn't just a ham thing - military message formats required CR CR LF

Messages were often punched on tape and then transmitted at 100 wpm.

Example message from a Navy Radioman training manual -

(5 SPACES 2CR LF)
PP RUHPC (2CR LF)
DE RUHPB 85 01/0841Z (2CR LF)
ZNR (2CR LF)

P 010837Z (2CR LF)
FM CINCPACFLT (2CR LF)
TO RUHPC/NWBJ/USS (2CR LF)
RENSHAW (2CR LF)
BT (2CR LF)
UNCLAS (2CR LF)
1. THIS PLAINDRESS (2CR LF)
SINGLE-ADDRESS MSG IS (2CR LF)
....

Nick England K4NYW
www.navy-radio.com

On Wed, Jul 23, 2025 at 10:07 AM John Nagle via GreenKeys <greenkeys@mailman.qth.net> wrote:

> From:"hwhall@aol.com" <hwhall@compuserve.com>
> Subject: Re: [GreenKeys] CR/LF trivia, in historical context
>
> radio amateurs made it a habit to send CR CR LF with the idea that 2 CRs
> gave sufficient time for even a slow machine to get back to the start
> of the line.
>
> Wayne
> WB4OGM
>