PHP delimiter <<<eof problem

PHP is a web programming language, in the programming process will inevitably encounter the use of echo to output a large segment of HTML and JavaScript script, if the traditional output method-by the string output, there must be a large number of escape characters in the string of quotation marks and other special characters to escape, Avoid syntax errors. If it is one or two can be tolerated, but if a full HTML text or a 200-line JS I think who will collapse. That's why PHP introduces a delimiter--at least for a large part of the reason.
The function of the 1.PHP delimiter is to follow the original, including the newline format, and output something inside it;
2. Any special characters in the PHP delimiter do not need to be escaped;
The PHP variable in the 3.PHP delimiter is replaced with its value as normal.
The delimiter format in PHP is this:
<<<eof
......
Eof;
Reasons for the error:
Not only EOF, no spaces at the front, and no spaces behind echo<<<eof.
<?php
$v = time ();
Echo <<<eof
<li><a href= "tabspage.html" target= "Navtab" > Frame panel {$v}</a>
..........
Eof;
?>

PHP delimiter <<<eof problem