Can I store custom data in $node->data? What is the purpose of $node->data? the Node object reference has $node->date, which used for 


  Long date, including timezone data, of when the node was created.


May I use $node->data to store my own temporary variables?
According to this page $node-&gt;data was used about Drupal 5 and is left there for legacy purposes only. It appears it's only purpose is to prevent "call to undefined property" errors. Do not use it.