The Browser service uses "Mailslots" and is perhaps the only
protocol that does. The mailslot "frames" are carried in SMB
"transact" packets. The opcode within the Transact SMB packet is
Mailslot Write. Within the data portion of the Transact packet is
the mailslot frame. The Transact data itself begins with an opcode
as shown below:
Table 1. Transact data opcodes
| Opcode |
description |
| 1 |
HostAnnouncement |
| 2 |
AnnouncementRequest |
| 8 |
RequestElection |
| 9 |
GetBackupListReq |
| 10 |
GetBackupListResp |
| 11 |
BecomeBackup |
| 12 |
DomainAnnouncment |
| 13 |
MasterAnnouncement |
| 15 |
LocalMasterAnnouncement |