The DICOM Editor, David Clunie informs that the 2015b release of the DICOM standard is now available from the NEMA ftp site:
ftp://medical.nema.org/MEDICAL/Dicom/current/
It is also indexed from the DICOM Editor's status page at:
http://www.dclunie.com/dicom-status/status.html
This replaces the 2015a release.
Release notes are at:
ftp://medical.nema.org/medical/dicom/current/output/pdf/releasenotes_2015b.pdf
The changes from the 2015a release are shown highlighted in PDF files; note that changes to figures are not detected and some changed figures are not rendered in the diff files:
http://www.dclunie.com/dicom-status/status.html#DiffsStandard2015a2015b