Just after jumping into the redoubt in Florida, Ryan happened to discover a piece of paper which appears to have codes on it. Over the next few days, they examine it off and on, but finally they discover the following titbits of invaluable information.
The first is the LD button which stands for Last Destination button. If this button is pressed before triggering the jump, the people using the gateway will be returned to the last gateway that was used. Example. Ryan takes Dean to stay with Jak and Christina Lauren in New Mexico. After dropping his son off, he hits the LD button before triggering the gateway and when he awakens, finds himself back in the redoubt in Florida.
There were the codes for several different location on the paper. They were listed as R1, R2 etc. which meant Redoubt. One is located in the south west of LA, but they don't want to risk that one as it is probably on the bottom of the Pacific ocean, and flooded.
The fourth is located in southern New Mexico, near Texas. This leads to the Redoubt that was destroyed (all but the gateway) in Time Nomads. This is the gateway located near Jak and Christina Lauren's homestead.
The fifth and final code reads "San I Sirdo" and has an eight letter code beside it.