One can add comments in the Information Link SQL in two ways:
Single-line comment: The comment should end in a single line.
Multi-line comment: Here, a comment can span over multiple lines.
The following screenshot gives an example of both the approaches.
When you write a single-line comment in Information Link SQL, you'll see that the comment is converted to a multi-line format in the SQL sent to the data source, as well in the SQL logs as shown in the screenshots below.
Information Link SQL:
SQL logged in the SQL logs: