how do I model a reminder of a future event?

Question

I am creating a capsule that will remind me and people in my contacts to vote on Election Day 2020. I am working on the models. I believe I need to model the concepts "Reminders" and "WhenPollsAreOpen". I am stuck on Reminders.

It seems to me that I want to create something like .reminder library capsule to handle reminding in general and then a specific model of reminding people to vote in elections.

structure (reminderPreferences) {
  description (preferences about a reminder)
  property (name) {
    type (Name)
    min (Required)
  }
   property (description) {
    type (Description)
    min (Required)
  }
  property (isactive) { 
  type (boolean)
  min (Required)
  }

I want the model to compile cleanly, but I get multiple "can't find type for property" error messagesenter image description here