Custom Metadata Type

1. Custom Metadata support most standard field types, but not support Rich Text.

2. Custom Metadata has 3 metadata types: 

Business Rule

Master Data

Mappings

3. The suffix for the custom metadata type is __mdt, the suffix for the custom field stays as __c

4.@IsTest(SeeAllData = true) annotation in Apex, this dangerous line of test code lets your       apex tests see all the records in your org.

5.Custom Metadata Relationship 

6. Protect Custom Metadata Types and Records :

权限问题: the package developer & Subscriber

7. Package Custom Metadata Types : upload package

8.Convert Custom Setting