Sources for dicom public dictionaries:
+ * the official source is the part 6 of the dicom standard (see
+ http://www.dclunie.com/dicom-status/status.html#BaseStandard2001).
* http://www.fpimage.com/Manuals/Imp/dicomdic.html
an html group based presentation.
* ftp://rsbweb.nih.gov/pub/nih-image/documents/dicom-dict.txt