Robert: When condos are first marketed ,  the sales staff, developer, surveyor, engineer, and title company all need to fully understand  how   unit numbering  ( and addresses)  work both on paper and in the field.  I have seen a project that was pre-sold with the unit numbering  starting West to East by the sales staff  except when  the final  surveyor/engineer drawings   were recorded  the unit numbering system started (and units sold) from East to West.  Sometimes these problems are not caught for years especially when the units are similar in size. What a mess!