This is the 4753rd most frequent German word.
zulässt
"Zulässt" means "allows" or "permits."
The word 'zulässt' indicates allowance or permission, describing that the time availability provides the boundary condition for efficiency.
Ich arbeite so effizient, wie es meine Zeit zulässt.
I work as efficiently as my time permits.
Here, 'zulässt' relates to the action permitted by the system, establishing the door's operability based on system authorization.
Die Tür öffnet sich nur, wenn das System es zulässt.
The door only opens if the system allows it.
In this context, 'zulässt' demonstrates personal consent or approval by the author regarding the book retention.