Is your feature request related to a problem? Please describe.

There is no way to define and communicate an exception Time Span that includes periods of time, based on our reading of the Time Span spec (exception periods are "externally-defined").

Describe the solution you'd like

We would like

• designated_period_except = true to indicate that a rule does not apply during the defined Time Span
• Time Span's with designated_period_except = true always supersede those with designated_period_except = false | null

Example 1: Time Span to communicate that a rule does not apply on Sundays:

{
    'days_of_week': ['sun'],
    'designated_period_except': true, 
}

Example 2: Time Span to communicate that a rule does not apply on New Years Day:

{
    'days_of_mont': [1],
    'months': [1],
    'designated_period': "New Year's Day",
    'designated_period_except': true, 
}

Is this a breaking change

A breaking change would require consumers or implementors of an API to modify their code for it to continue to function (ex: renaming of a required field or the change in data type of an existing field). A non-breaking change would allow existing code to continue to function (ex: addition of an optional field or the creation of a new optional endpoint).

• I'm not sure (edit: no)

Impacted Spec

For which spec is this feature being requested?

• Curbs

Describe alternatives you've considered

There does not appear to be any other way to communicate the actual time period of the exception Time Span.

Additional context