if(defined("LINK_ID"))
  print("ERROR");
$link_id = OCILogon(.....);
define("LINK_ID" , $link_id);

If I run this script it will print ERROR on the second call (refresh) but not the 3rd, then again on the 4th.
It seems not to like me assign the resource id in this form. If I use 
define("LINK_ID" , "$link_id");
it works and I can use the constant but this is hardly as documentated.
All other defined variables even those with simple strings or numerals carry over as well when I use the first method. Not nice :)
Since I already have a work around this is not a hot issue, but I would like to know if this is a problem with me or with php.
If you need more info please feel free to contact me.