Is it possible to place a comment line or note in the macro script?

Yes. Use the Remark command in Macro Express 3 or Comment command in Macro Express 5 and Macro Express Pro.

The comments are displayed in the Script Editor with blue text so that they will stand out from the rest of the script.

In addition to the above, Macro Express 5 and Macro Express Pro also allow you to add comments to the end of the command, rather than as a separate line in the script. Highlight the command and click on Edit | Comment or click on the Comment icon to insert the comment.