The Ad-lib system is a feature used predominately in Resident Evil Outbreak and Outbreak File #2. This system mapped various pre-selected phrases to the right analog stick and the L2 Button, allowing the player to communicate with their teammates. In online play, this system was used instead of traditional voice chat. Resident Evil 4, 5, and 6 used similar features so that player characters could communicate, though the latter two use voice chat for online play. But unlike the ad-lib system they are not as comprehensive.
In both Outbreak games there a multiple ways to communicate with other players or AI-controlled characters that are usually spoken verbatim unless the character naturally says it more politely or urgently. Male characters speak with green text while female characters speak with yellow text.
Normal Ad-lib (as seen in the image). Had soundbites in the original Outbreak but was made silent in the US version of the sequel. In the European version, the voices can be heard but the text is missing. Can be pressed at any time to gain hints or simply let the character make an observation. Square Button in Outbreak, Triangle Button in File #2.
"Help". Right Analog tilted left.
"Thank you". Right analog tilted right.
"Go." Right analog tilted up.
"Come on." Right analog tilted down.
"Wait". R3 (pressing the analog stick like a button).
"Yes." L2 + tilting the analog stick down.
"No." L2 + R3.
Call First Ally; L2 + tilting the analog stick left.
Call Second Ally; L2 + tilting the analog stick up.
Call Third Ally (Online play only); L2 + tilting the analog stick right.
"Sorry" (Exclusive to File #2); L2 + Triangle.
How responsive AI teamates can be is determined mostly by their respective "personalities". Mark will not respond positively to Kevin for instance, but will respond positively for David.