For CPC, similar to IT, if a problem isn’t reported, it is hard to argue that anything needs to be fixed. 

The primary reporting mechanism is CFAS (via the CPC webpage’s contact link (internal)).   That contact link also provides the TC’s POCs and other POCs.  Your SPE and QN should also be available to discuss any problems.

CPC scheme and definitions revision requests can be made at http://espstrain/sites/EXM/CPC/default.aspx
 
CAT (classification allocation tool, chrome only, http://prod-cpcdb.uspto.gov/mcc/secure/index.html#/home) has a lot of features and is underutilized.  This is where the USPC-CPC crosswalk will go.  It’s also useful for looking up the classification picture for an document family, applying symbols to a document, looking up QNs, and managing “my cpc” collections.

For POPA inquiries, please contact Gabriel Chu (Gabriel.chu@uspto.gov), our point of contact for CPC questions/concerns.