What is indicated by the revision block on a blueprint index?

The revision block on a blueprint index serves to document any modifications that have been made to the original drawing. This is crucial for maintaining an accurate record of the project's development and ensures all stakeholders are aware of the latest changes.

Each revision typically includes a description of the change, the date it was made, and possibly the initials of the person who implemented it. This documentation is essential for tracking the evolution of the project design, helping prevent confusion and ensuring that everyone involved is working from the most current set of plans. It enhances communication among architects, engineers, contractors, and clients, thereby minimizing the potential for errors during construction or project execution.

The other options refer to different aspects of a blueprint but are not directly related to the purpose of the revision block. Project deadlines pertain to scheduling, dimensions relate to the size and scale of elements within the design, and material specifications detail what materials should be used—none of which specifically indicate changes made to the drawings.