Overview of the document validation process
The user can initiate the validation process by clicking the Check Diagram button on the Process tab. The process will clear any existing issues for any changed pages in the document before looping through any rule sets . A changed page, sometimes referred to as dirty, is one that has shapes on it that have been altered in some way since the last validation. After validation, the process will re-mark as ignored any issues that were previously marked as ignored.
Any custom validation rules for a rule set should be executed in code whenever the relevant RuleSetValidated
event is fired. Visio does not automatically clear all issues in the document when the user selects the Process | Check Diagram button. It only clears issues for pages that are dirty, that is those that have had shape changes since the last time it was validated.
Note
If you are writing code to validate your rule set, then you could just iterate through any existing issues to delete...