The authorities scrutinized three generations of each detainee’s family, as well as their neighbors and friends. Officials in charge of monitoring mosques reported on how actively the residents participated in ceremonies, including the naming of children, circumcision, weddings and funerals.

The list specified whether detainees learned about religion from parents and grandparents or elsewhere. Dozens were listed as having a “heavy religious environment” at home — a designation that was often followed by a recommendation that they not be released.

The authorities also studied how many times a day detainees prayed and whether they took part in — or were even interested in — religious pilgrimages.

Outward signs of piety were also recorded. “Wore a beard from March 2011 to July 2014,” reads a description of one detainee related to several people who had been sent to camps. Officials categorized as “trustworthy” another man, the father of two detainees, who had cut off his beard and started drinking alcohol after a year of abstaining.

The entries offer detailed explanations of why officials ordered each person to be sent to a camp — information that has previously mostly trickled out through accounts by former detainees and activists.

Officials dissected their movements or plans to travel, particularly to predominantly Muslim nations. Even obtaining a passport was flagged, regardless of whether it was used. One of the most common reasons cited for detention, little known until now, was the violation of China’s birth restrictions by having too many children.

Some detainees were sent to indoctrination camps for crimes like drug sales or domestic violence. Others were put into camps because they had previously served prison time, including one man who finished his sentence nearly two decades ago.