What is a common format for external documents assigned to WBS elements?

The correct choice is Excel, as it is a widely used format for managing and analyzing project-related data, making it particularly suitable for external documents assigned to Work Breakdown Structure (WBS) elements. Excel's versatility allows users to create detailed spreadsheets that can include complex formulas, charts, and tables, which are commonly utilized in project management for tracking budgets, timelines, and resource allocations.

Using Excel for WBS elements allows project managers to effectively organize and manipulate data. It provides a familiar interface for many users, facilitating collaboration and ease of use when sharing information with stakeholders. Moreover, its compatibility with other software and systems means that Excel documents can be easily integrated into various project management tools and platforms.

While PDF and HTML formats are useful for presenting documents and web content respectively, they are not as effective for interactive data manipulation, which is crucial for project management tasks. XML is primarily used for data storage and transport rather than direct use for documentation in project management contexts. Thus, Excel stands out as the most practical format for external documents tied to WBS elements.