Is the prayer of zawal an independent Sunnah, or is it the Sunnah prayer that precedes Dhuhr, and what are the schools of thought of the people of knowledge, especially the four madhhabs, regarding this?

The scholars hold two opinions regarding the four rak'ahs after the sun's zenith and before the Dhuhr prayer. Some consider them an independent Sunnah called "Sunnat Az-Zawāl" (Sunnah of the Zenith), distinct from the Dhuhr supererogatory prayers. They base their view on narrations that describe it as an independent prayer during which the gates of heaven are opened. In contrast, the majority, including the Hanafis and some contemporary scholars, hold that these are the pre-Dhuhr regular Sunnah prayers.