## Reference
Block Editor

A block is a collection of trials. The Block Editor is where:

- You decide if and when the trials within the block should be randomized in the Randomize tab

- Cause a block to "loop" until a certain condition is met

- Create macros for more advanced control of the experiment's flow

### When to Run Tab

The options in the When to Run tab let you do two main things:

- "Filter" trials by building an "expression" and then telling SuperLab to present the next trial in the block Only if the condition expression is true or Only if the condition expression is false.

- "Loop" continuously While the condition expression is true or While the condition expression is false. If necessary, SuperLab will start the block all over again (loop) and keep presenting trials until the condition expression is satisfied. The following screen snapshot shows a block where trials will be presented for 5 minutes:

The When to Run tab provides a simplified interface to conditional branching and is sometimes all that's needed. Much more flexibility is available by using macros (see below). See the Expression Editor for more information.

### Macros Tab

The Block Editor's Macros tab is where all macros are created and link to a block. You can create as many macros as you need and use only the ones that you need for that particular block; example:

- Click on the New (+) icon button to create a new macro

- Use the Up and Down arrows to rearrange the order in which macros are executed

- Click on the Run this macro popup menu to decide when the macro should be executed
  IMPORTANT: changing this setting (as well as moving macros up or down) affects ALL blocks and not just the one you are editing.

Only the macros that have their blue checkbox turned on will be executed for that particular block.

### See Also

- Expression Editor

- Macro Editor