"operable to" pitfalls

Prouse's appeal focused on overcoming a 102(b) rejection of certain pending claims. Claim 1 recited:
1. A system in an electronic device for emitting light from a light-emitting diode (LED) at a variable brightness, comprising:

a waveform generator for generating an LED signal waveform comprised of a plurality of LED signal values; and

a processing unit operable to determine a scaling value for one or more LED signal values in the plurality of LED signal values, wherein the scaling value scales the one or more LED signal values based upon a percentage of a particular LED brightness.
The BPAI stated that "speculation and conjecture must be utilized by us and by the artisan inasmuch as independent claim 1 on appeal does not adequately reflect what the disclosed invention is." In analyzing the claims, the Board compared the "processing unit operable to determine" against the method claim that positively recited determining the scaling values. They stated:
In direct contrast to the positive statement of determining in independent claim 9, a processing unit is merely recited in independent claim 1 to be “operable to determine a scaling value.” Thus, it is merely capable of performing the recited or desired function of determining a scaling value. In other words, there is no present tense, positively recited determination of a scaling value in claim 1. Thus, since the scaling values are not actually determined, they cannot be used to scale the LED values as recited in the claim. This situation clearly renders the entire subject matter of independent claim 1 and its respective dependent claims 5-8 indefinite within the second paragraph of 35 U.S.C. § 112.
In view of the above, the Board reversed the Examiner's anticipation rejection of claims 1 and 9 and those claims depending from the independent claims. However, the Board issued a new ground of rejection with respect to claim 1 under the second paragraph of 35 U.S.C. § 112.

I don't think the use of "operable to" was the problem here. Rather, it was "operable to" in combination with the clause "wherein the scaling value scales the one or more LED signal values based upon a percentage of a particular LED brightness."

The question is, how can the scaling value do any scaling when its existence isn't certain?

I would try to fix this by saying something like "wherein the processor is further operable to scale the one or more LED signal values based upon a percentage of a particular LED brightness using a determined scaling value."

From http://bpaiwatchdog.blogspot.com/2009/04/processor-operable-to-peform-function.html#comments