keyword in if-then-else
If there is more than one condition then keyword elseif is usefull. If there is more than one elseif then the first true condition is selected (even other also are true).
a=1;
if a==1 then
`disp`_("a equals 1")
elseif a==2 then
`disp`_("a equals 2")
elseif a==1 & a>0 then
`disp`_("this condition is true, but never will be selected, because it is the second true condition.")
else
`disp`_("Case not handled.")
end