If then else in XML Publisher using parameter--Help need

Question

Hi
I am using xml data template in xml Publisher .we have three different layout in a rtf . we have three parameter P1, P2, P3 ,based on the parameter , the layout should display .
if P1 is not null then
display Layout1(one rtf contain 3 layout)
if P2 is not null then
display Layout2(one rtf contain 3 layout)
EXP. If p1 is not null then the 1st layout in rtf should display and rest two layout should suppress.
Similarly if p2 is not null then 2nd layout in rtf should display and rest two layout in rtf should suppress.
Please guide me how to implement this in rtf layout.
SS

Answer 1

At the top of your template put the following:
<?param@begin:P1?><?param@begin:P2?><?param@begin:P3?>
Assuming that if P1 is not null, P2 and P3 are both null...
Put <?if:$P1!=’’?> or <?if:$P1!=’NULL’?> before the beginning of your layout1. You may have to try one and then the other, or use NULL without the quotes, depending on what is returned in your xml data.
Put <?end if?> at the end of your layout1.
Repeat the same steps for layouts 2 and 3. Remember to change the P1 to P2 or P3 as needed.
Haresh