# Help understanding the information field in an APRS-IS message

I'm looking at the raw packet data from http://aprs.fi. I see packets such as these:

ROSLDG>APN390,HEBOWX,OR2*,qAR,MKSRDG:@015805z4501.34NF12351.41W_000/000g000t053r000p000P000h92b......U2k
W7KKE-9>TTRSUT,NEWPRT*,OR2-1,qAR,W7GC-3:'4]. {nv/]"3z}
KG7HEL-3>AAAPPP,WIDE1-1,WIDE2-1,qAR,BEAVRT:'vX<0x1c><0x1c> <0x1c>#/>TEMP1-1 digi running on battery= [Latitude and longitude are both 0]


Where is the specification for the information that comes after the : at the end of the path information? I can find a specification for APRS data as it is packeted into an AX.25 packet, but not for the messages that come from an APRS-IS server. Can I assume that anything after the : is in the same format as the Information Field in the APRS AX.25 specification? What happens to non-printables?

I've surmised that the ' and @ after the : are APRS Data Type Identifiers, but I have no idea what the <0x1c> stuff is in the last packet.