There are descriptions on "System Interface Requirements for arrowhead" - 4.5. Notes on Test Issues.
(Excerpt below)
The main purpose of Test Issues is provided as the failure recovery in Connectivity Test. Each Trading Participant can place approximately 1,000 orders per Test Issue per day although the test orders are placed by the other reasons.
If there is a large amount of orders on Test Issues, TSE may halt their tradings without prior notice to reduce system workload.
When the trading of Test Issues is halted, Warning Information (Trading Halt Info) Message is not sent to Virtual Servers.
(Test participants can recognize a trading halt in the Test Issues is happened when placing orders via Virtual Server (Order/Notice) and returned as an Order Acceptance Error Code (Reason Code = 1002: Trading Halt) or the Error Notice is able to be identified from On-demand Query Order Book Request via Virtual Server(Query)).
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