Mic-E TYPE CODES                                         14 July 2008
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When the APRS SPEC was written, there were only a few types of Mic-E
products in use.  These were the original Mic-E prototype, the TAPR
Mic-E kit, and the two Kenwood radios, the D7 and D700.  Since the
Mic-E format uses the AX.25 TOCALL Address field for Latitude and
other information, the normal APxxxx version number cannot be used to
indicate the type of Mic-E device or version number.

Therefore, the first byte of the free-field text was set-aside for
use in indicating the type of Mic-E device.  On page 55 of chapter 10
of the spec, the first two of these TYPE CODES were defined for the
Kenwood radios.  In addition, the statement was made:

"It is envisioned that other Mic-E ccompatible devices will be
allocated their own type-codes in the future."

The future has arrived and it is time to maintain a table of the use
of this byte in the identification of Mic-E type devices.  

VERSION CODE:  The first issue that arose was the need to identify 
the new D710 as being part of the D700 family, but then having new 
capabilities.  Since all existing software, firmware and other APRS 
radios would already recognize the D700, it was decided not to 
change that TYPE CODE for new radios in that series, but to instead, 
append a special character onto the end of the status text instead.  
This allows for new distinct models in the same familiy to be added, 
without having to re-define new TYPE CODES.

CHARACTERS:  It is important to note, that since these TYPE CODES
cannot be pre-defined until the product is produced, these TYPE CODE
Bytes will appear in displays as the leading byte in free field 
text.  So therefore, characters must be chosen that when taken at
face value as the leading byte in a text field, they will not cause
confusion in interpretation of subsequent text.  The following table
suggests possible characters not only for this leading TYPE CODE
byte, but also for possible trailing VERSION CODE bytes.

VALID TYPE CODE AND VERSION CODES.  For the purpose of this spec,
the written format of "T...V" will be used, where "T...." is the
text that can fit in the free-text field of a Mic-E packet.  And
where "T" is the TYPE CODE, "..." is any text of any allowed 
length, and "V" is an optional trailing VERSION CODE.

 ....  Original Mic-E (leading space)  (not message capable)
>....  TH-D7A walkie Talkie            (message capable)
]....  TM-D700 MObile Radio            (message capable)
]...=  TM-D710 Mobile Radio            (message capable)

/....  Avail
^....  Avail
)....  Avail
\....  Avail
'....  Avail
`....  Avail
:....  Avail
;....  Avail
~....  Avail
_....  Avail

It is important that the type of Mic-E device be identified, since 
some may have very important distinct properties.  One of the most
crucial differences is to distinguish between those devices that
are message capable or not.

Designers of Mic-E type devices are encouraged to advise their 
intent to use one of these codes so that other designers can 
include them in their parsing table for display.

This table is maintained on the APRS web page:
http://www.ew.usna.edu/~bruninga/aprs/mic-e-types.txt

Bob Bruninga
WB4APR@amsat.org