Chinese Language Day (20 April)

中文日快樂！
Zhōngwén rì kuàilè!
Happy Chinese Language Day!  (thanks,GT)
"...established by the UN in 2010 (on 12 November)...moved to this day in April the following year..."
No explanation of the "why" of either date. But:
"The date was chosen to honour Cangjie, a legendary figure who is said to have invented Chinese characters 5,000 years ago."
and
"The day is the beginning of a period in the Chinese calendar called _Guyu_, the sixth of the twenty-four terms that make up the calendar. The name means "rain of millet", as, according to legend, when Cangjie invented the characters, the gods wept tears of joy and the sky rained millet."
https://en.wikipedia.org/wiki/Cangjie