<...> proprietary attribute "..."

Cause:

The tag contains an attribute that is proprietary to Netscape or Internet Explorer.

Solution:

Most tags have a equivalent in standard HTML or CSS.


Tag
 Proprietary attribute
 Standard attribute
<body>
 marginwidth=0
marginheight=0
leftmargin=0
topmargin=0
 style="margin: 0px"
<frameset> border=0
frameborder=0
framespacing=0
 None with frameset. See here.
Use a HTML table with iframe for the same result.
<table>
 height=100%
 style="height: 100%"
<td>
 background="abc.gif"
 style="background-image: url(abc.gif)"




Sample: <table> proprietary attribute "height"


BAD    <table height="100%">
GOOD   <table style="height: 100%">


References:

None