Viewing the source in a browser to investigate anomalies
This suggestion rightfully belongs in the troubleshooting chapter, but it is inserted at this point because of how useful it can be when debugging forms and pages.
On occasion, a form or page looks fine in Designer, but the rendered results are not correct. This can happen because Domino sometimes generates HTML code that you may not expect. Or perhaps an error message displays indicating that some field or variable is undefined.
If rendered results are anomalous or if the behavior of a form is not what you expect, it can be helpful to look at the web page source for clues, either with a simple editor or with a browser's developer tools. For example, here is a simple page consisting of a heading and an image. The HTML is marked as Pass-Thru HTML:
Here the computed text @formula supplies part of the source value for the image that displays on the page. There are other ways to include images on pages, of course. This construction is intended...