I found this info on the Academy of Medical Surgical Nurses web site.
ANCC (ANA's credentialing center) is one of about 40 boards/centers that offer certification examinations in various nursing specialties. All of these boards offer nationally standardized examinations that are prepared using accepted testing standards (Standards for Educational and Psychological Testing (1999), published jointly by the American Educational Research Association, American Psychological Association, and the National Council on Measurement in Education). ANCC offers the largest number of tests (between 30 & 40, including separate tests for AD/diploma and baccalaureate-prepared nurses).
[FONT=Verdana,Arial,Helvetica,sans-serif]Many of these boards are members of the American Board of Nursing Specialties (ABNS), the "board of boards," (similar to the National Board of Medical Examiners), which accredits nursing certification boards. A representative of MSNCB will be attending the ABNS meeting in February. MSNCB plans to join and have its examination accredited by ABNS.
A large numbers of nurses are certified by boards other than ANCC, e.g., AACN for critical care nursing, BCEN for emergency nursing, OCN for oncology nursing, and NCC (National Certification Corporation) for women's health nursing. The NCC offers ten different exams in women's health, and ANCC offers five in critical care. Both NCC and ANCC offer exams in neonatal critical care. ANCC and NCBPNP (National Certification Board of Pediatric Nurse Practitioners and Nurses) offer both exams in pediatric nursing. Now exams in med-surg nursing will be offered both by ANCC and MSNCB.