+ o Support ISO INTERVAL syntax if units cannot be determined from
+ the string, and are supplied after the string
+
+ The SQL standard states that the units after the string
+ specify the units of the string, e.g. INTERVAL '2' MINUTE
+ should return '00:02:00'. The current behavior has the units
+ restrict the interval value to the specified unit or unit
+ range, INTERVAL '70' SECOND returns '00:00:10'.
+
+ For syntax that isn't uniquely ISO or PG syntax, like '1' or
+ '1:30', treat as ISO if there is a range specification clause,
+ and as PG if there no clause is present, e.g. interpret '1:30'
+ MINUTE TO SECOND as '1 minute 30 seconds', and interpret
+ '1:30' as '1 hour, 30 minutes'.
+
+ This makes common cases like SELECT INTERVAL '1' MONTH
+ SQL-standard results. The SQL standard supports a limited
+ number of unit combinations and doesn't support unit names in
+ the string. The PostgreSQL syntax is more flexible in the
+ range of units supported, e.g. PostgreSQL supports '1 year 1
+ hour', while the SQL standard does not.
+