The National Cemetery Administration now uses D/2. Quote: "The NCA entered into an agreement with the National Center for Preservation Technology and Training, NPS, to evaluate marble cleaners in an effort to minimize damage to historic headstones. The 3-phase study began in 2004 and was completed in 2011. The best - practice recommendations resulted in NCA's determination to use the preferred cleaner, D/2 Biological Solution…" (Page 3)
From Presidential Executive Order 13287, Preserve America FY 2011 Triennial Report Department of Veteran Affairs.