This article provides detailed explanations of the Comment Reports available in PPO:
The report includes all the fields on the Comments entity for all comment records and projects. If the “Include Project Information” checkbox is selected, the report will also include all the fields on the project entity. This report is only available in datasheet view.
The Comment History report provides a complete overview of how the various comments have changed over the lifespan of the project. The report can also be filtered further to only include comments related to certain projects. This report is available in report view, datasheet view and PDF view.