The validoverlap feature adjusts the tolerance of the overlap test between signed and unsigned items performed by the Viewer when signing items. The overlap test looks for signed items that overlap unsigned items. You should always follow the best practice of signing as much of the form as possible. This means that if your form fails the overlap test, you should first consider whether you can sign additional items to correct this problem.
Lines can often cause problems. In general, you should either sign all lines in the form, or sign none of the lines in the form. This will help you avoid problems with lines that overlap each other. If you choose to sign none of the lines in the form, you may need to adjust the placement of some lines to prevent them from overlapping with other items, such as fields. While this may seem like a lot of work, it's preferable to signing the overlapping line. Signing the line may create more problems than it solves, as the line may overlap with a number of other lines which may overlap with further lines, and so on. Because of the work involved in determining which lines need to be signed, it's best to avoid this scenario if possible.
Because unsigned items might be moved later to reveal information that changes the meaning of the form, the overlap test prevents the user from signing these forms. However, in some cases the overlap is very slight and should be allowed. If you still find that you cannot sign your form because of overlapping items, you should adjust the
validoverlap setting by small increments (such as 1 or 2 pixels) until you can successfully sign the form, or until you reach an overlap of 8 pixels.
Usage Notes
Never set the
validoverlap to allow more than 8 pixels of overlap. If you find that you still cannot sign your form with an overlap of 8 pixels, the form should be redesigned so that items do not overlap as much. Using a larger
validoverlap increases the risk that a malicious user could successfully modify a signed form.
The
validoverlap can also be set as low as 0 (zero) pixels. The default of 2 pixels accounts for the size of a border, which is included in the size of each item, even if the border is not drawn.
Exceptions to this practice
There are no exceptions to this practice.