note jZed You wrote:<p> <blockquote> <table
border="1"><tbody><tr> <td>Entity</td> <td>Attribute</td>
<td>Value</td> </tr></tbody></table> </blockquote> </p> While
there are some cases in which this is a good idea, it can also
lead to really confused things like this: <p> <table
border="1"><tbody> <tr> <td>Entity</td> <td>Attribute</td>
<td>Value</td> </tr> <tr> <td>Elephant</td> <td>Color</td>
<td>Gray</td> </tr> <tr> <td>Workstation</td>
<td>Linux_distro</td> <td>Debian</td> </tr> </tbody></table>
</p> <p> What happens to constraints and data types when each
new row potentially introduces a new data type? What meaning
does the concept "entity" have if there are no limits on the
kinds of attributes it can take and the range and type of data
the values for those attributes can have? I realize that you
know what you're doing and probably only use this kind of a
table in appropriate circumstances (and you did specify an
example in which there were multiple optional attributes which
is not the same as the exampl