Sounds like OP just wants to find out more about how travel agents operate. Nobody seems to have answered him (I don't know well enough so I can't say).
Sounds like he wants to tell a story, not to find out
Actually, I'll tell you what it actually sounds like. It sounds like OP just found out that the way that travel agents have access to availability that is not open to the general public is by using a GDS. Then somebody sent him a link to the Amadeus training book (which can be found by google search.)
https://www.google.com/#q=amadeus+gds+manualThis made OP think, "Hmmm, I wonder if this could be exploited somehow? I know, the guys at DDF probably know." So instead of just posting, "Guys, can Amadeus be exploited by a non-TA?" he was more subtle and just said, "Let's talk about how travel agents book tickets..." He then threw in some info (sort of) -- "as of my knowledge, travel agents book tickets through a booking program called "Amadeus" -- thereby presenting himself as someone who was bringing info to the table and not merely grasping at straws and fishing for others to cough up all the info. Oh, and then he threw in some proof of his insider knowledge -- "I have got a link to a training booklet of the program" -- which echoes his opening words of "let's talk about...." which makes it sound as if a conversation
were to actually start, OP would be able to contribute to it further.
Just my take.