From Test-Scratch-Wiki

The general shape of a Cap block.

A Cap block is a block that is designed to stop a script or project from running, cancelling unwanted activity before it can start.

The Cap blocks

There are two Cap blocks, both located in the Control category. They are:

— stops either everything, the script or the other scripts in the sprite. If "stop other scripts in sprite" is selected, it becomes a stack block.

— stops all the scripts that the clone is running and deletes the clone


As Cap blocks are designed to stop a script or project, their bottom is smooth; no blocks can be placed under them, as there is no need. Other than that, their shape is identical to the Stack block — they still have the notch on the top, so the block can be placed below others.

Making A Cap Block

The coding in the System Browser blockspecs for a cap block is the same as a stack block. To make the bottom smooth, the method at the location Scratch-Blocks >> CommandBlockMorph >> accessing >> isStop must be edited. Add:
| (selector = #method)
and accept.


The need to stop a script (or all scripts) can be found in several occasions. Some include:

  • Disabling a script that will continuously set a variable
  • Once a game is completed, all scripts stop
  • Deactivating a sprite

An example follows:

set [Letter v] to [0]
repeat (length of (answer))
   change [Letter v] by (1)
   if <(letter (Letter) of (answer)) = [z]> then
      stop [this script v]

Note how the Cap block (Stop ()) is used — if the selected letter is "z", the script stops.

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