0,print,'oo'
if,MEM[0] == 0,
0,print,'AA'
else if,MEM[0] == 1,
0,print,'BB'
else if,MEM[0] == 2,
0,print,'CC'
else,,
0,print,'DD'
end if,,
1,print,'xx'
User should set "Eval mode" to "Yes". The string "MEM[0] == 0" will be eval to get true or false. The start of if-block is "if", the end of if-block is "end if". Now it noly supported one level if-block, it did not support nested if-block.
Note that, user should not put any tag in the if-block.