Specify default of [period]

Author: jhpratt

diagrams/diagrams.py

@@ -59,7 +59,7 @@ def __init__(self, name, diagram):
 case_sensitive = Sequence("case_sensitive:", Choice(0, "true", "false"))
 hour_repr = Sequence("repr:", Choice(0, "24", "12"))
 month_repr = Sequence("repr:", Choice(0, "numerical", "long", "short"))
-period_case = Sequence("case:", Choice(0, "lower", "upper"))
+period_case = Sequence("case:", Choice(0, "upper", "lower"))
 sign = Sequence("sign:", Choice(0, "automatic", "mandatory"))
 subsecond_digits = Sequence(
     "digits:", Choice(0, "1+", "1", "2", "3", "4", "5", "6", "7", "8", "9")

src/api/format-description.md

@@ -250,8 +250,8 @@ ASCII whitespace characters.
 
   ![syntax for period component](../diagrams/period.svg#rr)
 
-  Users have the option to choose whether the value is uppercase or lowercase. This component is
-  typically used in conjunction with the hour of the day with `repr:12`.
+  Users have the option to choose whether the value is uppercase (the default) or lowercase. This
+  component is typically used in conjunction with the hour of the day with `repr:12`.
 
   When parsing, there is the option to consume text-based formats case-insensitively.