《宋书·志·卷十五》
到了晋代泰始四年时，尚书何桢上奏说： 已故皇帝举用的公府主簿等官吏，不管是去职的官员或前往别处任职的官员，都要为已故皇帝反服齐衰丧服三个月。 
至晋太始四年，尚书何桢奏： 故辟举纲纪吏，不计违适，皆反服旧君齐衰三月。 
In the fourth year of the Tai Shi Era of the Jin dynasty, the Minister of the Imperial Secretariat He Zhen submitted a memorial stating: For the officials who served the deceased Emperor including the Master of the Imperial Secretariat, no matter whether they are those who have left office or those who have taken up posts elsewhere, they should observe a three-month mourning period for the deceased Emperor, wearing plain clothes made of haircloth.
<s>[INST] Kindly elucidate the central themes in this passage in English: 至晋太始四年，尚书何桢奏： 故辟举纲纪吏，不计违适，皆反服旧君齐衰三月。  [/INST] In the fourth year of the Tai Shi Era of the Jin dynasty, the Minister of the Imperial Secretariat He Zhen submitted a memorial stating: For the officials who served the deceased Emperor including the Master of the Imperial Secretariat, no matter whether they are those who have left office or those who have taken up posts elsewhere, they should observe a three-month mourning period for the deceased Emperor, wearing plain clothes made of haircloth.</s>
Kindly elucidate the central themes in this passage in English: 至晋太始四年，尚书何桢奏： 故辟举纲纪吏，不计违适，皆反服旧君齐衰三月。
user
In the fourth year of the Tai Shi Era of the Jin dynasty, the Minister of the Imperial Secretariat He Zhen submitted a memorial stating: For the officials who served the deceased Emperor including the Master of the Imperial Secretariat, no matter whether they are those who have left office or those who have taken up posts elsewhere, they should observe a three-month mourning period for the deceased Emperor, wearing plain clothes made of haircloth.
assistant