The clone troopers of the Republic Military were given regulation manuals on how to act, with the clones themselves referring to the guides as "reg manuals." The manuals could be read on datapads and they featured an entry on what a unit was to do without their sergeant present. One rookie clone trooper, Echo, enjoyed reading the manuals and did so in Rishi Station on the Rishi Moon of the Outer Rim.
Readable on datapads, regulation manuals were given to the clone troopers of the Republic Military to educate them on how to behave. One entry covered what a clone unit should do if their sergeant was unable to command them. The clones took to shortening the manuals' title when speaking about them, calling the guides "reg manuals."
Echo read the regulation manuals prior to the battle on the Rishi Moon.
During the galaxy-wide Clone Wars between the Galactic Republic and Confederacy of Independent Systems, Echo, a clone trooper stationed at the Rishi Station outpost on the Rishi Moon in the Outer Rim, was very focused on protocol, the regulation manuals, and his orders. In fact, Echo had received his nickname from his habit of repeating regulations and orders.
One day in 22 BBY, Echo walked into the station's command center while reading one of the manuals. When heavy weapons expert and fellow rookie Hevy complained about the lack of combat on the moon, Echo revealed he enjoyed their station's peace, citing that it allowed him to catch up on the manuals. The comment confused Hevy, who rebutted by saying their purpose was to fight against the Separatist Droid Army. When another rookie, Cutup, joked that Echo had been kept in his growth chamber for too long, Echo was annoyed and turned his attention back to the manual until Clone Sergeant O'Niner spoke up.
A short time afterward, the station was attacked by a team of BX-series droid commandos, resulting in the deaths of many clones stationed in the outpost. O'Niner was among those killed, making trooper Fives question what to do. Echo began to recite what the regulation manuals ordered, only to be interrupted by a Rishi eel that killed Cutup.
The regulation manuals first appeared in "Rookies," the fifth episode of the first season of the animated television series Star Wars: The Clone Wars, which first aired on October 24, 2008. They were first identified by their full name in the StarWars.com episode guide for "Rookies." In a behind-the-scenes featurette for the episode, Supervising Director Dave Filoni joked that Echo's strict adherence to the regulations made him a maintenance duty clone. The StarWars.com article for their rewatch of "Rookies" framed Echo's strict adherence to the rules as his rookie mistake, making him the opposite of the eager-to-fight Hevy. According to the blog post, Echo had nervous responses to anything that bent the rules because he had yet to understand they should only be a guideline.