Shoot.
Not working.
If you 'View Source', you can see the variables and values are properly appended to the link, but when you mouse over the link you can see that the link shows up as incomplete in the browser's status line (lower left hand corner of browser).
Thus, "page1.php?cat=Books&sub_cat=Romance&get_sub_cat=yes" shows up as "page1.php?cat=Books" and gets sent to the browser that way.
However, for some reason, "page1.php?cat=Books&get_sub_cat=yes" is being sent correctly.
Here's the specific code. Since the page calls itself, at the top, I have:
urldecode($sub_link);
urldecode($link);
and in the body:
$link="<a href=\"page1.php?cat=$cat_from_db&get_sub_cat=yes\"><font size=\"2\" face=\"Verdana\" color=\"black\" class=\"Text1\" onmouseover=\"this.style.color = 'red'\" onmouseout=\"this.style.color = 'black'\"><b>$cat_from_db</b></font></a><br>\n";
urlencode($link);
print "$link";
$sub_link=" <a href=page1.php?cat=$cat&sub_cat=$append_sub_cat&get_sub_cat=yes><font size=\"2\" face=\"Verdana\" color=\"black\" class=\"Text1\" onmouseover=\"this.style.color = 'red'\" onmouseout=\"this.style.color = 'black'\">|-$append_sub_cat</font></a><br>\n";
urlencode($sub_link); print "$sub_link";