Here you will find the postmasks for some Synchrotrons Labs in the world. If you find the others ones, please add to this folder, or send me the coordinates to update this post.
Best regards, Narcizo.

Brazil:
LNLS (Laborat�rio Nacional de Luz S�ncrotron)

Canada:
Canadian Light Source (CLS)

U.S.A. :
National Synchrotron Light Source (U.S.A.)
Stanford Synchrotron Radiation Laboratory
Advanced Light Source
Advanced Photon Source

Europe:
ELETTRA Synchrotron Light Laboratory
MaxLab
Swiss Light Source
SOLEIL
Diamond Light Source
DESY (The German electron synchrotron)
ESRF (European Synchrotron Radiation Facility)