R help - Sep 2004 - extRemes; what data is ftcanmax?

Heya,

  sorry, if I ask the obvious, but I did not find it anywhere.

What Prec got measured here? What real-life observation
is behind that data?

----------
library(extRemes)
data(ftcanmax)
ftcanmax
 > data(ftcanmax)
 > ftcanmax
    Year Prec
1   1900  239
2   1901  232
3   1902  434
etc.
-------

Thanks,
  -Armin