1. The half boundary has not been provided yet, but will be provided for each of the test files and will be posted on the data site. “Missing” means some of the log lines representing faults are not provided.
2. Yes, logging delays may occur in all data sets. A logging delay should be strictly less than 15 minutes. So In your example, the logging time is 2009/8/18 18:30:00 (line 13 in plant_1a.csv) does not appear to include any delay. Consider the actual time to be logging time “modulo 15 minutes.”