Final answer:
The question pertains to building codes regulating the landing dimensions at a doorway when a door is fully open. The exact number of inches permissible is not provided and can vary, but the requirement is important for safety and accessibility in building design.
Step-by-step explanation:
The question relates to building codes and the specifications that must be adhered to when constructing or remodelling structures such as homes or businesses, specifically in regard to the landing dimensions at a doorway. Buildings codes often specify that doors in the fully open position must not reduce a required landing dimension by more than a certain number of inches to ensure safety and accessibility. Unfortunately, the specific number of inches is not mentioned in the question; it varies depending on local building codes and regulations, but typical values can be around 0 to several inches. This requirement ensures that the door, when open, does not impede the landing space which could potentially be a hazard or interfere with the movement of people, particularly those with disabilities.