At the beginning of the siman, Maran touches on the idea of שחרית בשעת נץ החמה. There are a number of important discussions on the topic in the Aharonim. Namely; Shaharit before Netz when the Sibbur is up all night; Netz Beyahid vs. Tefila Besibur afterwards or before the Netz; The importance of Tefila BaNetz and the calculation of the Netz.
