StaticMAXVALUEspec Part 3 says:
The same sequence number shall not be reused on a Subscription until over four billion NotificationMessages have been sent. At a continuous rate of one thousand NotificationMessages per second on a given Subscription, it would take roughly fifty days for the same sequence number to be reused. This allows Clients to safely treat sequence numbers as unique.
SequenceNumberGenerator manages a monotonically increasing sequence number. SequenceNumberGenerator
See
OPC Unified Architecture, Part 6 - $6.4.2 page 36 -
The SequenceNumber shall also monotonically increase for all messages and shall not wrap around until it is greater than 4294966271 (UInt32.MaxValue – 1024).
The first number after the wrap around shall be less than 1024.
Note that this requirement means that SequenceNumbers do not reset when a new TokenId is issued.
The SequenceNumber shall be incremented by exactly one for each MessageChunk sent unless the communication channel was interrupted and re-established.
Gaps are permitted between the SequenceNumber for the last MessageChunk received before the interruption and the SequenceNumber for first MessageChunk received after communication was re-established.