I don't think you can have a value like that on your submit button (or are you trying to have the button display the text on it?). What you might try doing is passing the variable in the url.
for example, if you wanted to pass variable $var with a value $row_doc["html"], you could do
<form name="form" method="post" action="">
<input name="Submit" type="submit" onClick="MM_openBrWindow('entry.php?var=<? echo $row_doc['html']; ?>','blorb','status=yes,width=400,height=300')">
</form>
I hope I didn't misunderstand your post, but that should get the variable over if your openBRWindow function works right.
Actually, if that's the case, you wouldn't even need a form
<input type="button" onClick="MM_openBrWindow('entry.php?var=<? echo $row_doc['html']; ?>','blorb','status=yes,width=400,height=300')">
Cgraz