A UMC message indicates that an uninitialized value is being copied from one memory location to another (e.g. an assignment). Such copies are normally harmless copying of padding fields in structures.
By default, Purify suppresses UMC messages in the global .purify file because they can generate excessive output and reduce your program's performance. To unsuppress UMC messages, comment out the line in the <purifyhome>/.purify file that reads:
suppress umc *
by adding a hash mark (#) at the beginning of the line:
#suppress umc *
or add the line:
unsuppress umc *
to the .purify file in the directory where your program resides.