Hi, first of all I've been wondering what illuminant and what observer angle the .cht files as shipped with ArgyllCMS are using. It's possible that I've overread that piece of information in the documentation. But as the Zen of Python also states: "Explicit is better than implicit." ... That also led me to the next: It would be good to explicitly be able to state certain conditions for the .cht file. Especiallyl illuminant and observer angle, possibly some more meta information, e. g. what batch or version a chart was, etc. Profilemaker (I believe) uses meta tags inside the file as this: ILLUMINATION_NAME "D50" OBSERVER_ANGLE "2" Is something like this possible for .cht files as well? Maybe that would make a sensible extension to the file format. Alternatively/additionally comments could be used in the file. E. g. a line starting with the hash "#" could be interpreted as a comment. Using that also version information of the file itself e. g. from CVS or Subversion could be managed ... Just my thoughts. Any ideas from anybody? Graeme? Guy -- Guy K. Kloss Institute of Information and Mathematical Sciences Te Kura Putaiao o Mohiohio me Pangarau Room 2.63, Quad Block A Building Massey University, Auckland, Albany Private Bag 102 904, North Shore Mail Centre voice: +64 9 414-0800 ext. 9585 fax: +64 9 441-8181 eMail: G.Kloss@xxxxxxxxxxxx http://www.massey.ac.nz/~gkloss/