25 November 2005: Changed the MED doses to conform to the paper of Fitzpatrick et al., 1988, after suggestion by an anonymous reviewer. 

11 December 2008: 
The method now applies the CIE vitamin D effective action spectrum. 
Reference: 
Holick, M, R. Bouillon, J. Eisman, M. Garabedian, J. Kleinschmidt, 
 T. Suda, I. Terenetskaya, A. Webb.
CIE Technical Committee 6-54 Technical Report 174 (2006) Action
spectrum for production of previtamin D3 in human skin.
Commission Internationale de l'Eclairage (CIE) Central Bureau.
Vienna, Austria, email: ciecb@ping.at
Also outputs the sunburn exposure time.

18 August 2011:
We have now also downscaled the above SDDs by a factor of 1/1.32 as suggested in John C. Dowdy,
Robert M. Sayre, Michael F. Holick, Holick's rule and vitamin D from sunlight, The Journal of
Steroid Biochemistry and Molecular Biology, Volume 121, Issues 1-2, Proceedings of the 14th
Vitamin D Workshop, July 2010, Pages 328-330, ISSN 0960-0760, DOI: 10.1016/j.jsbmb.2010.04.002.
(http://www.sciencedirect.com/science/article/pii/S0960076010001925). They obtained a more
accurate fluorescent sunlamp emission spectrum for the underlying in vivo experiments.