Use of catalog config.xml product collection attributes
I inherited a highly customized Magento 126.96.36.199 system. The company that customized and installed the system made there changes both in a local module AND by modifying core code. We are now in the process of unwinding the core code changes in order to be able to upgrade to a more current version. Adding insult to injury they did not document there changes.
I have been using WinMerge to find the core code changes, restore the original version and re-implement the changes in local modules. Most of the time I can figure out what they were trying to do with the change. My mode of operation is to save the changed code, restore the original 188.8.131.52 code and test to see that the change they implemented is no longer working (i.e. core code is being picked up). I then implement and enable the local module and test to see that the local module change is being picked up.
I recently came across a change to app/code/core/Mage/Catalog/etc/config.xml in which they added an attribute to <frontend><product><collection><attributes>. I know how to make a local change to implement this additional attribute, but am unable to figure out what this change affects so that I can test the before and after (as described above).
Can someone explain the use of the <frontend><product><collection><attributes> values in app/code/core/Mage/Catalog/etc/config.xml? Where would I see the manifestation of this list of attributes? My Google searches aren't turning up anything specific except some mention of the product flat data which is not enabled in our system. Thx.