MPDOT is documented on the Symbian Foundation website. See:
http://developer.symbian.org/wiki/index.php/DocTools/MPDOT

MPDOT Version 0.1.6
===================
Fixed defect: Updated doctype to latest dtd version (0.6.0).

MPDOT Version 0.1.5
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Added build directory for MPDOT. Publication is now put in root of out dir.
Adding MPDOT macro to common.xml

MPDOT Version 0.1.4
===================
Updated script to be compatible with latest DITA C++ Specialisation DTDs (v0.6.0)
Added publishing to eclipsehelp format.
Changed structure of output (now named output dir (given by user) and a build dir).

MPDOT Version 0.1.3
===================
Added quoting on command line for directories that have spaces in them.
Added format="html" to DitamapLinkConverter converted html links for DITA-OT compatibility.