Jerry, hopefully someone will post a tidy explanation of how a recursive CTE works. In the meantime, run this SQL to see the entire contents of the 'l' table:

with l as (

select 32 as i, char(32) as s, isnumeric(char(32)) as n

union all

select i+1, char(i+1), isnumeric(char(i+1)) from l where i < 127

)

select * from l

That should help you begin to understand what's going on.