Versions 6.8.x and 2003.x
Method comments were introduced in 1993 with 4D Insider 1.0. This version allowed you to add comments to your methods. The comments we are talking about here are not those that you can add in your methods between two lines of code, but those attached to a specific method. Back to 4D Insider 1.0, the name for this comments was "Documentation".
In 4D Insider, if a method is displayed with its name underlined, it means that the method has a documentation attached to it.
Since version 6.5 of 4D, you can see these comments in the Explorer window. To display these comments for a given method, select that method from the method list and select the "Comment" radio button. You can also define an automatic comment system if you wish. You may want to check the tech tip "4D v6.5 Automatic Comments" for more details.
Starting with 4D 2003, comments can be used with SOAP methods. When you publish a SOAP method, you can also provide its documentation in your WSDL; this is usually done to explain how to use that method. To do so, 4D 2003 will grab the first 256 characters of a SOAP method's comments and use them as documentation.