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The possibilities for a given guideline are outlined in the following table below.
The final possibility is that a tool has not implemented a checker for a specific guideline.
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While many guidelines list common exceptions, it is difficult if not impossible to develop a complete list of exceptions for each guideline. Consequently, it is important that source code comply with the intent of each guideline and, to the greatest extent possible, tools minimize false positives which positives that do not violate the intent of the guideline. The degree to which tools minimize false-positive diagnostics is a quality-of-implementation issue.
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