[GreenKeys] Navy abandons M28 compatibility

[Nick England]

The U.S. Navy is changing the format of messages to include lower case
characters.

http://www.navytimes.com/article/20130606/NEWS04/306060010/ALL-CAPS-MESSAGES-no-more

"The Navy and other services have a long history with all-caps
messages. Early teletype machines, which the military started using in
the 1850s, were made up of only three rows of keys and did not allow
for lowercase letters."