The following table has been used to initialize the actions registry.
+-----------+------------+----------------------------+
| Action | Status | Reference |
+-----------+------------+----------------------------+
| AUDIO | Current | RFC 5545, Section 3.8.6.1 |
| | | |
| DISPLAY | Current | RFC 5545, Section 3.8.6.1 |
| | | |
| EMAIL | Current | RFC 5545, Section 3.8.6.1 |
| | | |
| PROCEDURE | Deprecated | [RFC2445], Section 4.8.6.1 |
+-----------+------------+----------------------------+