Unfortunately, the designers of some systems seem never to have bothered to read the DICOM standard.
DICOM has from the start had the facility to include icon images in C-FIND requests, but it is rarely used.
DicomObjects is commonly and successfully used for Anonymisation and all the required data changes are easy using DicomObjects - the real problem is working out what needs changing!
Private Elements (or Tags) are perfectly legal in DICOM, details of the structure of Private DICOM Elements can be found in DICOM Private Elements.
Removing all Private elements from any DICOM instance is quite simple, following sample code shows you how to do it in DicomObjects.
There are many times when users need to know how many objects there of a given type, without needing to enumerate each one.
Mask subtraction is very different in the COM and .NET versions of DicomObjects