Weekend Learning: RAC patching skipping database defined as ORACLE_HOME

In a continued effort to expand what I might know in a Support role, or what the term even means, I have been keeping my eyes open for nuggets of information that I can add to leverage in the future.  Tonight the My Oracle Support article "Why "opatch auto" not patching RAC database ORACLE_HOME?" via note ID 1479651.1 is one such type of nugget as I typically do not get to look at patching (opatch), ORACLE_HOME, or even GI (Grid Infrastructure) so this is another sneak under the covers of what is happening "at the database level".