Adding line breaks in Title attribute

I am trying to add line breaks in a buttons Title attribute, so that
when the user hovers over a specific button it will display the
information, (but w/ line breaks). I am able to get the information to
appear in the title but line breaks don't work for some reason. Below
I have the code I am currently using. Any attempt I have made to add
line breaks doesn't seem to pay off for me. I am sure I am just
missing the easy answer.



 document.write('<button id="item{@num}" title="{first_name}
{last_name} {order_disposition}" onmouseover="tabMouseOver(this);"
onmouseout="tabMouseOut(this);" content="item{@num}Div"
onclick="javascript:checkOrderStatus('+ statusCount +
');javascript:showItemAt(' + _tabCount +
');javascript:updateCurrentUsers('+ {order_detail_id} + ');">');
    document.write('<xsl:value-of select="external_order_number"/>');
    document.write('</button>');


Thanks, for you assistance

Carl