What's going on in the Dhyana Hall: Actual Facts Edition

Today an r/zen regular wrote an OP that hypothesized "what actually went on in the 'Chan Hall'." However, none of their supporting quotes actually mentioned the Chan/Dhyana/Sangha Hall. Strange, huh?

We like facts, so let's look at facts. What do historical records tell us about these halls?

The following is from an analysis of the *Chanyuan qinggui* (Rules of purity for Chan monasteries), compiled in the second year of the Chongning era (1103) by Changlu Zongze.

>At the time when Wuliang compiled this work, he held the monastic office of head seat (shouzuo), which meant that he was in charge of leading the so-called “great assembly” (dazhong) of ordinary monks who had no administrative duties, and thus were free to concentrate on a daily routine of meditation, study, and devotions. The rules found in the Riyong qinggui pertain almost exclusively to the facilities where the monks of the great assembly of a public monastery spent the majority of their time. The most important building for them was the sangha hall (sengtang), where each monk had an individual place (tan) on the platforms. **There the monks sat together in meditation, took their morning and midday meals as a group, and slept at night**...

>...Sleep was minimized and long periods of sitting meditation (zuochan) were held.

There we have it. No guessing required.