OT: (x)?html question

[Don Russell]

Sorry for this somewhat off topic message, but I've had no luck 
elsewhere... :-(

I thought there was a way in html to define an "entity" and then use 
that throughout the document.

So, for example I might have something that appears in multiple places 
but I only want to code it once:

I was thinking of something like...
<meta entity="callno" content="1(123)555-1212"/>

Then I could use &callno; in the body of the document and the browser 
would properly substitute the specified value.

I suppose I could write a little javascript function and then use 
<script>...</script> to call it as needed and the function would use 
document.write.... but that really is overkill, and I'd prefer not to 
REQUIRE javascript.

Any suggestions?

Thanks for the diversion from our regular program. :-)