public client examples are any OAuth clients where the client secret cannot be kept confidential (e.g. a native application or SPA). Particular examples include the Synapse programmatic/command line apps and the GWT client.
Possible requirements (not a complete list)
Additional grant types
The requirements are likely to be heavily informed by the OAuth 2.1 draft: https://tools.ietf.org/html/draft-parecki-oauth-v2-1-02#section-7.3.1