You're welcome JoeJoe.
What I'm doing is using the red-black tree implementation, or "contexts as dictionaries". This is a common idiom in newlisp, very fast and easy.
So the question is, is a schedule unique. What do you mean by "allow another user to access the schedule". Does a schedule always belong to one and only one user?
Cavemen in bearskins invaded the ivory towers of Artificial Intelligence. Nine months later, they left with a baby named newLISP. The women of the ivory towers wept and wailed. "Abomination!" they cried.