AWK quiz

How come every post in this forum is a request for help?
How about some fun?

What does the following command do?

nawk -F'[^A-Za-z_]+' '
{i=NF;for(;i;i--)if($i)w[tolower($i)]++}
END{
  for(k in w){c=w[k];x[c]=x[c]k",";if(c>m)m=c}
  for(;m;m--)if(m in x)print m,x[m]
  }
' <(man nawk)

In most shells it produces a syntax error.

You know that's not the point.

 
man awk | awk ...

Now, what does it do?