So far, I found there are some interesting ways to search in global structure:
InterSystems FAQ rubric
The TIMESTAMP type corresponds to the %Library.TimeStamp data type (=%TimeStamp) in InterSystems products, and the format is YYYY-MM-DD HH:MM:SS.nnnnnnnnn.
If you want to change the precision after the decimal point, set it using the following method.
1) Set system-wide