Think about the following code example:
htmlHelper.InputHelper(InputType.CheckBox, name, "true", true /* useViewData */, false /* isChecked */, true /* setId */, false /* isExplicitValue */, htmlAttributes);
This line is taken from the source code of ASP.NET MVC, or to be more specific its a line from the InputExtension class. I think the intent of the original developer is clear:
Add comment next to arguments so that one can easily read the method call without getting lost in a who's who since there are quite some arguments to pass.
To learn more about named parameters using C#, you can visit this post by ScottGu.