Editing NMEA 0183 (section)

== Message structure ==
* All transmitted data are printable [[ASCII]] characters between 0x20 (space) to 0x7e (~) 
* Data characters are all the above characters except the reserved characters (See next line)
* Reserved characters are used by NMEA0183 for the following uses:
{| class="wikitable"
|-
! ASCII !! Hex !! Dec !! Use
|-
| <CR> || 0x0d || 13 || Carriage return
|-
| <LF> || 0x0a || 10 || Line feed, end delimiter
|-
| ! || 0x21 || 33 || Start of encapsulation sentence delimiter
|-
| $ || 0x24 || 36 || Start delimiter
|-
| * || 0x2a || 42 || Checksum delimiter
|-
| , || 0x2c || 44 || Field delimiter
|-
| \ || 0x5c || 92 || TAG block delimiter
|-
| ^ || 0x5e || 94 || Code delimiter for HEX representation of ISO/IEC 8859-1 (ASCII) characters
|-
| ~ || 0x7e || 126 || Reserved
|}
* Messages have a maximum length of 82 characters, including the $ or ! starting character and the ending <LF>
* The start character for each message can be either a $ (For conventional field delimited messages) or ! (for messages that have special encapsulation in them)
* The next five characters identify the talker (two characters) and the type of message (three characters).
* All data fields that follow are comma-delimited.
* Where data is unavailable, the corresponding field remains blank (it contains no character before the next delimiter – see [[#Sample file|Sample file]] section below).
* The first character that immediately follows the last data field character is an asterisk, but it is only included if a checksum is supplied.
* The asterisk is immediately followed by a [[checksum]] represented as a two-digit [[hexadecimal]] number. The checksum is the [[Bitwise XOR|bitwise exclusive OR]] of [[ASCII]] codes of all characters between the ''$'' and ''*'', not inclusive. According to the official specification, the checksum is optional for most data sentences, but is compulsory for RMA, RMB, and RMC (among others).
* [[Newline|{{code|<CR><LF>}}]] ends the message.

As an example, a waypoint arrival alarm has the form:
: ''$GPAAM,A,A,0.10,N,WPTNME*32''

Another example for AIS messages is:
:!AIVDM,1,1,,A,14eG;o@034o8sd<L9i:a;WF>062D,0*7D