The variable in question contains the full url of the referring page. I was trying to determine if the string contained within that variable was a url from my own domain or was from another site. (=/= was shorthand for "does not equal").
I've done some more work and it now works perfectly. The only trouble now is that code seems horribly bloated. I've went from two lines of code in my very first menu to 9 lines in the code I posted earlier and now to this crazyness:
<?php
if(strstr($link,'oceandots') && (isset($sub))){
echo "<div id=\"menu_large\">\n";
echo "<ul>\n";
gmv_menu();
echo "<li><a href=\"$link\">$place</a> > </li>\n";
echo "<li>location map</li>\n";
echo "</ul>\n";
echo "</div>\n";
echo "</div>\n";
}
elseif (strstr($link,'oceandots') && (is_null($sub))){
echo "<div id=\"menu_large\">\n";
echo "<ul>\n";
gmv_menu();
echo "<li>location map</li>\n";
echo "</ul>\n";
echo "</div>\n";
echo "</div>\n";
}
elseif(strstr($link,'oceandots') === false && (isset($sub))){
echo "<div id=\"menu_large\">\n";
echo "<ul>\n";
echo "<li>$place ></li>\n";
echo "<li>location map</li>\n";
echo "</ul>\n";
echo "</div>\n";
echo "</div>\n";
}
elseif(strstr($link,'oceandots') === false && (is_null($sub))){
echo "<div id=\"menu_large\">\n";
echo "<ul>\n";
echo "<li>$place ></li>\n";
echo "<li>location map</li>\n";
echo "</ul>\n";
echo "</div>\n";
echo "</div>\n";
}
?>
As I said at the top, this works and the problem I had no longer exists. But I can't help but feel I've taken an awfully long-winded approach to do something relatively straightforward.