dateto_stream(os, fmt.c_str(), tp).
from_stream formatting
-Each flag begins with a %. Some flags can be modified by E or
-O. During parsing each flag interprets characters as parts of date and time
-type according to the table below. Some flags can be modified by a width parameter which
-governs how many characters are parsed from the stream in interpreting the flag. All
-characters in the format string which are not represented in the table below are parsed
-unchanged from the stream. The C++ specification says that the parsing of month and
-weekday names is both locale sensitive and case insensitive. If you find this not
-to be the case, file a bug with your std::lib vendor.
+All from_stream overloads behave as an unformatted input function. Each
+overload takes a format string containing ordinary characters and flags which have special
+meaning. Each flag begins with a %. Some flags can be modified by
+E or O. During parsing each flag interprets characters as parts
+of date and time type according to the table below. Some flags can be modified by a width
+parameter which governs how many characters are parsed from the stream in interpreting the
+flag. All characters in the format string which are not represented in the table below,
+except for white space, are parsed unchanged from the stream. A white space character
+matches zero or more white space characters in the input stream. The C++ specification
+says that the parsing of month and weekday names is both locale sensitive and case
+insensitive. If you find this not to be the case, file a bug with your std::lib vendor.