Limit determines the kind of constraints which will ultimately bring a story to a conclusion.

For an audience, a story’s limit adds dramatic tension as they wonder if the characters will accomplish the story’s goal. In addition, the limit forces a Main Character to end his deliberations and Change or Remain Steadfast.

Sometimes stories end because of a time limit. Other times they draw to a conclusion because all options have been exhausted. Running out of time is accomplished by a Timelock; running out of options is accomplished by an Optionlock.

Both of these means of limiting the story and forcing the Main Character to decide are felt from early on in the story and get stronger until the moment of truth.

Optionlocks need not be claustrophobic so much as that they provide limited pieces with which to solve the Problem. They limit the scope of the Problem and its potential solutions.

Timelocks need not be hurried so much as they limit the interval during which something can happen. Timelocks determine the duration of the growth of the Problem and the search for solutions.

Choosing a Timelock or an Optionlock has a tremendous impact on the nature of the tension the audience will feel as the story progresses toward its climax.

A Timelock tends to take a single point of view and slowly fragment it until many things are going on at once.

An Optionlock tends to take many pieces of the puzzle and bring them all together at the end.

A Timelock raises tension by dividing attention, and an Optionlock raises tension by focusing it. Timelocks increase tension by bringing a single thing closer to being an immediate problem, Optionlocks increase tension by building a single thing that becomes a functioning problem.

One cannot look just to the climax to determine if a Timelock or Optionlock is in effect. Indeed, both Time and Option locks may be tagged on at the end to increase tension.

A better way to gauge which is at work is to look at the nature of the obstacles thrown in the path of the Protagonist or Main Character. If the obstacles are primarily delays, a Timelock is in effect; if the obstacles are caused by missing essential parts, an Optionlock is in effect.

An author may feel more comfortable building tension by delays or building tension by missing pieces. Choose the kind of lock most meaningful for you.

From the Dramatica Theory Book