[Fpga-synth] Simple Filter Question

[Scott Gravenhorst]

"The making of synthesizers in FPGAs." wrote:
>Scott Gravenhorst wrote:
>> Rick Huang <rhuang at newsguy.com> wrote:
>>> I can't help it but to put it through the matlab...
>>>
>>> Rick
>> 
>> Ah, thanks, and now I have to go through a few Octave tutorials so that I can do this
>> myself.  Obviously, from the graphic, it's a lowpass.
>
>octave:4> freqz([0.8895 0.1087], [1 0.0136])
>
>Will plot out passband, stopband and phase.

Ok, this certainly works.  But I don't understand the second parameter: