This is an overview ticket for feature requests / bugs related to Calendar Sharing:

Sharing

• Allow (internal) sharing of subscribed webcal calendars #1600
• Federated calendar and contacts sharing #1440
• Can not delete group shared calendars (and addressbooks I guess) #1653
• Accept or decline calendar shares through notifications #19568
• group member can overwrite private appointment #5551
• Share calendar to users or groups with "show only as busy". #11214
• Per-user settings for shared events #19827
• Contacts Birthday calendar should be shareable
• Send invitations for shared calendars #26668
• Support calendar sharing via MacOS Calendar.app #5050
• Can't add myself to a shared event calendar#2659

Publishing

• Allow editing on publicly shared calendars #3509
• Share calendar to users or groups with "show only as busy". #11214

Features missing for feature parity with file-sharing:

• Share with e-mail address
• Option for forbid resharing
• expiry date
• Add note to sharee
• #27545 password protect (public)
• Hide download (public)