Closed sets and regular sets are common pattern types, both of which are significantly easier to parse than complex patterns. Closed sets have a predefined set of values which would allow one to enter data statically (such as states, countries, or capitals). Regular sets match regular expressions but are often too numerous to make enumeration worthwhile (such as phone numbers or shipping tracking numbers). Complex patterns such as postal addresses may be recognizable for humans but difficult to interpret for machines
-Christophe
