The Twelve Day Officers (Jian Chu)
The twelve day officers are among the most familiar entries in a Chinese almanac. Their order, where each month's count starts, and which are good or bad, following the Imperial Almanac (Xieji Bianfang Shu).
The order of the twelve
The twelve day officers are among the most familiar entries in a Chinese almanac. Each day has one, in the order Establish (建), Remove (除), Full (满), Balance (平), Settle (定), Hold (执), Break (破), Danger (危), Success (成), Receive (收), Open (开), Close (闭), repeating every twelve days. The Imperial Almanac quotes the calendar makers:
厯家以建除滿平定執破危成收開閉凡十二日周而復始觀所值以定吉凶
— Imperial Almanac (Xieji Bianfang Shu), 建除十二神
Where the count starts
Each month, Establish falls on the day whose branch matches the month's branch, and the rest follow in order. The first month is the Yin month, so Establish starts on a Yin day, Remove falls on the Mao day, Full on the Chen day, and so on:
正月建寅則寅日起建順行十二辰
— Imperial Almanac (Xieji Bianfang Shu), 建除十二神
Months here change at the solar terms: the first (Yin) month begins at the Start of Spring and the second (Mao) month at the Awakening of Insects, not on the first day of the lunar month. On the day a new month begins, the officer repeats, so two days in a row share one officer and the new month's count starts on the right day:
每月交節則疊兩值日
— Imperial Almanac (Xieji Bianfang Shu), 建除十二神
Which are good and which are bad
The book's commentary divides the twelve into good and bad:
除危定執成開為吉建破平收滿閉為凶
— Imperial Almanac (Xieji Bianfang Shu), 建除十二神
Remove, Danger, Settle, Hold, Success and Open are good; Establish, Break, Balance, Receive, Full and Close are bad. The good or bad mark beside the day officer on this site follows this division. The book also quotes the Huainanzi on each officer, showing how old the system is:
淮南子曰正月建寅則寅為建夘為除辰為滿已為平主生午為定未為執主陷申為破主衡酉為危主杓戌為成主小德亥為收主大德子為開主太陽丑為閉主太隂
— Imperial Almanac (Xieji Bianfang Shu), 建除十二神
Is the day officer enough?
No. The day officer is only one of the many spirits of a day. The book says to weigh how many good and bad spirits a day has, then look at what each spirit favours or forbids:
大抵凡日吉神多則吉凶神多則凶又各視其神之宜忌以為趨避
— Imperial Almanac (Xieji Bianfang Shu), 建除十二神
So this site's favourable and unfavourable activities combine all of the day's spirits, not the day officer alone. How that works is explained in "How the almanac's activities are decided".
All quotations in this guide are from the Imperial Almanac (Xieji Bianfang Shu) and have been checked against the book; other explanations are compiled by this site.