Secretary of the Interior’s Standards for Rehabilitation   The basic purpose of the Standards is to maintain the primary character-defining elements of a property. They generally do not require the restoration of missing elements; rather, they are designed to allow for changes that are needed to adapt a building to a new function. A property will be used as it was historically or be given a new use that requires minimal change to its distinctive materials, features, spaces and spatial relationships. The historic character of a property shall be retained and preserved. The removal of historic materials or alteration of features and spaces that characterize property will be avoided. Each property shall be recognized as a physical record of its time, place, and use. Changes that create a false sense of historical development, such as adding conjectural features or architectural elements from other buildings will not be undertaken. Changes to a property that have acquired historic significance in their own right will be retained and preserved. Distinctive features, finishes, and construction techniques or examples of craftsmanship that characterize a historic property will be preserved. Deteriorated historic features will be repaired rather than replaced. Where the severity of deterioration requires replacement of a distinctive feature, the new feature will match the old in design, color, texture, and other visual qualities and, where possible, materials. Replacement of missing features shall be substantiated by documentary and physical evidence. Chemical or physical treatments, if appropriate, will be undertaken using the gentlest means possible. Treatments that cause damage to historic materials will not be used. Archeological resources will be protected and preserved in place. If such resources must be disturbed, mitigation measures will be undertaken. New additions, exterior alterations, or related new construction will not destroy historic materials, features and spatial relationships that characterize the property. The new work shall be differentiated from the old and will be compatible with historic materials, features, size, scale, proportion, and massing to protect the integrity of the property and its environment. New additions and adjacent or related new construction will be undertaken in such a manner that, if removed in the future, the essential form and integrity of the historic property and its environment would be unimpaired.