Yes, certain characters denote processes and will terminate the line. For exampe, a "+" is called an "end item" and ends the line, and starts a new line (without a carriage return) so they can't use the "+" in the field. Slashes also cause problems as do about 1/2 of the symbols.

The software is and has been for a decade moslty on well designed but rather simple GUI that makes most of the info "fill in formats" by using a combination of hundreds of menus. The GUI translates this into the raw apollo commands that were used up until the mid to late 90's.
PNR's (reservations-Passenger Name Records) have many "freeform fields" where non-programed data can be entered (most often in your phone field or in an OSI.)

FT'ers have reported that they have been able to see comments put in their records when agents enter them in "public" fields that the "owner" (agency/passenger) of the reservation has access to. Agents SHOULD not put information like this in these fileds...there are propriatary areas that should be used for sensitive information.

I use "**" to set a freeform comment/information apart so it stands out from the pre-formatted stuff. If you want something to be noticed and it looks like every other piece of standard data, one needs to be observant to pick it out. Us some "**" and spaces and blank lines to isolate, and it is seen much more clearly. Like when you log onto a mainframe, there usually is alot of junk data, and if the admin wants you to see something they will surround it with "***" and put a blank line ahead and after to frame it.
And Ice, "Probably coded though, something like "S*UAL/PLLW.MLK"" only pulls up the internal profile on how to serve the pillows/milk. The actual request is a SSR (special service request) that is standarzed across all carriers (so automations can pick it up and connecting airlines can give the pillow/milk as well.) But we all know, they don't have the proper training as to how many pillows and what kind of milk, that UA has.