Basic dates for Work Breakdown Structure (WBS) elements can be planned manually using several standard tools within the SAP Project System (PS) module. The Project Builder (Transaction CJ20N) is the central tool for creating and editing all project objects. Within the Project Builder, you can select a WBS element and manually enter the basic start and finish dates on its detail screen. The Project Planning Board (Transaction CJ27) provides a graphical Gantt chart interface. It allows for the visual planning and adjustment of dates, where users can change the basic dates of WBS elements by graphically manipulating the bars or by entering dates in the corresponding table section.

A. Schedule Manager: This is a cross-application tool used for planning, automating, and monitoring recurring background jobs and complex business processes, such as period-end closing, not for manual project date planning.

D. Easy Cost Planning: This tool is used for quantity-based cost estimation and planning within a project. Its primary function is to plan costs, not to schedule or maintain project dates.

1. SAP S/4HANA 2021 Documentation, SAP Help Portal: "Project Builder". This official documentation describes the Project Builder (CJ20N) as the primary, user-friendly interface for maintaining all project data, which includes manually entering dates for WBS elements in their respective detail views. (Path: SAP S/4HANA -> Enterprise Portfolio and Project Management -> Project System (PS) -> Structures -> Project Builder).

2. SAP S/4HANA 2021 Documentation, SAP Help Portal: "Project Planning Board". The documentation details the Project Planning Board as a graphical tool for planning and controlling projects. It explicitly states that users can create and process WBS elements, including their dates, within this Gantt chart environment. (Path: SAP S/4HANA -> Enterprise Portfolio and Project Management -> Project System (PS) -> Dates -> Project Planning Board).

3. SAP S/4HANA 2021 Documentation, SAP Help Portal: "Basic Dates". This section explains that basic dates for WBS elements can be entered manually or determined by top-down or bottom-up scheduling. The tools for manual entry are specified as the Project Builder and the Project Planning Board. (Path: SAP S/4HANA -> Enterprise Portfolio and Project Management -> Project System (PS) -> Dates -> Date Determination in the WBS -> Basic Dates).