Date: 5/8/2008 11:47 am EDT
I can't seem to get my brain wrapped around this.
Most door openings have casings that terminate the baseboard, but not in all cases. The tile (meeting other floor coverings) usually is addressed with trim only between the casings/door jambs and the tile also usually dives into the door opening. Either slightly or to the center of the door jamb or wall.
When transitioning from tile to another floor covering midspan of a baseboard you can sometimes remove the base to raise it (atop the tile) at the transition-point and install a decorative block at that location. This block is a means of ecusing the change in elevation of the baseboard.
Or, install the tile and then add shoe mold only on top of the tile leaving the baseboard in tact everywhere.