In general, DNG files embed the XMP information inside them, however, it need not be so. For example, IIRC C1 uses an external XMP sidecar file with DNG files, and Adobe software can support this mode of operation as well if you lock the DNG files (make them read-only), something that is directly supported by Adobe Bridge's GUI (contextual right click).
It is my understanding that PM does not support this mode of operation. I ask you to consider supporting this mode of operation in future versions of PM.
This mode of operation is extremely useful when using version control systems, or certain backup software. In general VCS software does not like large binary files that constantly change. This creates too much churn and requires too much storage to keep all the versions. VCS and backup software work very well with rarely changing large binary files (DNG, other kinds of raw files, etc), and small sidecar files that change frequently. In fact I believe this is the reason Adobe supports this mode of operation. Some very large Adobe clients use Perforce for their VCS.
FastRawViewer, a software I use often in conjunction with PM and Adobe software already supports this mode of operation.
Thank you!
