Excuse me, what does the RE of RETSRA mean in aviation meteorological specification?

I only know that it is a format of airmail, and RE is a fixed format, which represents the weather in the past period of time, and may also have the meaning of report. For example, there are some codes: REFZDZ REFZRA REDZ ... and so on, and there are many weather phenomena: weather phenomena can be divided into current weather and recent weather. The so-called current weather phenomenon refers to the weather phenomenon that exists during observation; Recent weather refers to the weather phenomenon that exists ten minutes before observation and does not exist at the time of observation. The weather description modifiers commonly used in actual situations, forecasts and special reports: weather phenomenon intensity or place description symbol precipitation phenomenon visual range obstacle other phenomena-slight, small and shallow DZ Mao Mao rain BR light fog PO dust/sand cyclone (dust wind) BC scattered RA rain FG fog medium intensity (unmodified) SN snow FU smoke FC funnel cloud (tornado) DR low blowing SG rice snow VA volcanic ash+strong, IC ice needle with big BL and high blowing DU floating dust DS sandstorm SH.