There seems to be several choices:
a) require browsers to differentiate each of the physical
styles (B, I, U, TT and S)
b) introduce <em1>, <em2>, ...<em4>
c) Use Bryan Oakley's FACE idea and require browsers
to differentiate a small set of style names
Right now, the simplest seems to use (a) and encourage browsers
to comply with differentiating the small set of existing physical styles.
Dave Raggett