Information is relayed around an APRS RF network by packet digipeaters. The unproto path is what invokes those digis. APRS defines generic aliases such as RELAY, WIDE, TRACE n-n and WIDE n-n.
Generic WIDE n-n
Example start: APRS,WIDE7-7
1st APRS,M0AAA*,WIDE7-6
2nd APRS,M0AAA*,M0BBB*,WIDE7-5
3rd APRS,M0AAA*,M0BBB*,M0CCC*,WIDE7-4
4th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,WIDE7-3
5th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,WIDE7-2
6th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE7-1
7th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,M0GGG*,WIDE7*
Advantages. You can plot digipeater paths and coverage. QRM drops because the digi adds its callsign, so it will not relay that packet again. Messaging has an easier return path.
Disadvantage. The frame gets larger and more prone to errors.
Generic GBR n-n
Example start: APRS,GBR7-7
1st APRS,GBR7-6
2nd APRS,GBR7-5
3rd APRS,GBR7-4
4th APRS,GBR7-3
5th APRS,GBR7-2
6th APRS,GBR7-1
7th APRS,GBR7*
Advantage. The frame stays the same size as the first transmission, so it often travels further.
Disadvantage. A lot of QRM — digis struggle to know whether they have already repeated the packet and often do it more than once. A checksum helps, but if the packet is heard again after the dupe window it will be digipeated again.
WIDE n-n then GBR n-n
Example start: APRS,WIDE6-6,GBR7-7
1st APRS,M0AAA*,WIDE6-5,GBR7-7
2nd APRS,M0AAA*,M0BBB*,WIDE6-4,GBR7-7
3rd APRS,M0AAA*,M0BBB*,M0CCC*,WIDE6-3,GBR7-7
4th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,WIDE6-2,GBR7-7
5th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,WIDE6-1,GBR7-7
6th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-7
7th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-6
8th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-5
9th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-4
10th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-3
11th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-2
12th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7-1
13th APRS,M0AAA*,M0BBB*,M0CCC*,M0DDD*,M0EEE*,M0FFF*,WIDE6*,GBR7*
A bit of column A and a bit of column B. That is a lot of hops even in this linear sketch. In reality the packet spiders outward, so this combination should not be used.