Initial connection string.  Server sends greeting with version number:

CVSLock 1.1 Ready

Commands are:

Login mode   1.0
Client <user>'|'<root>['|'<client_host>]

Register a lock client.  This must be done before any other commands (except monitor) are
executed.

Client mode   1.0
Lock {Read|Write} [Recursive] {File|Directory}'|'<path>

Start a lock on a file or directory.

Client mode   1.0
Unlock <path> [{Read|Write} [Recursive] {File|Directory}'|'<path>]|'All'

Terminate a lock.   This is also called implicitly if you break connection to the lockserver

Login mode   1.0
monitor [C][L][V]

(1.1 only) C - Monitor Client login/logout (default)
(1.1 only) L - Monitor Locks (default)
(1.1 only) V - Monitor Version changes

Monitor activity.

State is sent to the client in the following format:

Login/Out: 010 MONITOR Client (client) server|client|user|root|state
Lock:      010 MONITOR Lock (client) Path|Flags  
Unlock:    010 MONITOR Lock (client) Path|Deleted 
Version:   010 MONITOR Version (client) Path|Branch|Version|Type

Monitor mode   1.0
Clients

(monitor mode only) List current lockserver clients.  Results are in the following format:

(client) server|client|user|root|state


Error returns:

000 OK {message}
001 FAIL {message}
002 WAIT {message}
010 MONITOR {message}


-------------------------------
protocol 1.1 extensions

client mode 1.1
Modified [Added|Deleted]'|'<RCS path>'|'<branch>'|'<version>

Error returns:

000 OK {message}
001 FAIL {message}