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This article has details about adding content to Reminders: Add a reminder from another app on Mac - Apple Support
Add a reminder from another app
When you add a reminder from another app, an app icon or link is added to the reminder. You can use that icon or link to get back to the item in the app where you created the reminder, such as a Safari webpage, Mail message, or Maps location.
1. While using an app on your Mac, select the item you want to remember, click the Share button
, then choose Reminders.
2. If the app doesn’t have a Share button, Control-click the item you want to remember, then choose Share > Reminders.
From the same article, " Note: In some apps, the Share menu doesn’t include Reminders, so you can’t use it to create a reminder for the selected item or location."
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