>> in the owners manual on page 28 (page 36 of the pdf) there is a note
>> which says: The 5 pedal functions are accessable by using the
>> optional
>> Polaris Control Panel (pln 30 3712-700).
>>
>> What is this?

Paul DeRocco's answer is the definitive one - but for what it is worth,
I can confirm that a (presumably) earlier version of the printed owner's
manual does not contain the referenced 'note' (nor any of the other
'NOTE:' portions in this chapter.)

That earlier(?) version similarly does not include some other items
found in the version on the Rhodes Chroma site (such as the Page 35
reference to the Lower Function 11 Warm Reset Switch, etc.)

That earlier doc was shown as copyright CBS in New York vs. the on-line
scan showing as copyright Fender in California.

The later document has Chapter 16 as "Troubleshooting" and Chapter 17 as
"Control Switch Dictionary" while the earlier document has Chapter 16 as
a listing of Polaris Patch names - with 17 and 18 being the
Troubleshooting and Control Switch dictionary sections.

I wonder if the reference in the on-line manual is actually an original
typo (in a couple spots) and was intended to read:

Polaris Control Pedal (P/N 30-5712-700)

Instead of:

Polaris Control Panel (pln 30 3712-700)

That would seem to make a bit more sense, and a few things support this.
First - a note from a Chroma Polaris 'Accessories' one-sheet has:

-----
CONTROL PEDAL (p/n 30-5712-700) $59.95 US Retail Price
This Pedal will provide access to the 5 programmable pedal functions of
the Polaris.
-----

The description here is essentially a reworded version of what's in the
referenced manual note.

Second - on page 35 of the manual there is a reference to 'THE PEDAL
(optional - Fender part no. 30-5712-700)'

David Clarke