Possible enumeration values:
| Name | Value | Description | 
|---|---|---|
| None | 0 | |
| In | 1 | |
| Out | 2 | |
| Lcid | 4 | |
| Retval | 8 | |
| Optional | 16 | |
| ReservedMask | 61440 | |
| HasDefault | 4096 | |
| HasFieldMarshal | 8192 | |
| Reserved3 | 16384 | |
| Reserved4 | 32768 |