Crystal has a function that calculates the drill-down level of the current window. This allows you to have objects and sections format differently at specific levels of drill-down. The function is called DrilllDownGroupLevel and it gives you a numeric value that tells you the current drill-down level for any preview tab.  The normal preview is level 0, the first drill-down is level 1, etc. So if you want a section with column headings to appear at the second level of drill-down and ONLY at the second level of drill-down you can use the following as a suppression formula for that section:

DrilllDownGroupLevel <> 2

That section will be suppressed in normal preview (drill-down level 0) and also at the first drill-down level, but will appear if you drill down again from level 1. If you are ever unsure which level of drill-down you are on you can write a formula that says simply:

DrillDownGroupLevel

Place this formula in the section in question. When you see that section the number shown will tell you the current drill-down level.

DrillDownGroupLevel also helps you solve one of the dilemmas of report design.  One of the lessons in my advanced class is how to have a report be either a detailed report or a summary report, based on a parameter prompt. You accomplish this with a parameter that has two choices (Summary/Detail) and you use that parameter in the detail section’s suppress formula. It has to be the suppress property because the “hide” property doesn’t have a condition formula button. And, because you are using the suppress property you can no longer drill-down from the summary version of the report to see the details for a group.

But by using the following as your suppress formula you can have the parameter to choose summary or detail, and still have drill-down available on the summary version:

{?Parameter} = "Summary" and
DrillDownGroupLevel <> 1

This will suppress the section when you choose “Summary”, but only as long as you are in the main preview tab.  As soon as you drill down the suppress condition will no longer be met and the details will be visible.