The Lookup parameter, in combination with a Lookup action, allows you to create a table that assigns values to labels. This can come in handy when a block comes in preset sizes. The Lookup parameter and action are based on another parameter/action pair, such as a Linear parameter and Stretch action. In essence, the Lookup pair sets the allowable values for a particular parameter/action pair. You can either create a value set to preset the values that are used in the lookup table or set the values when you create the lookup table.
To use a Lookup parameter, open or create a block in the Block Editor and assign the parameter/action pair (for example, Linear parameter and Stretch action). If you want, create a value set for the parameter.
Next, add a Lookup parameter from the Parameters tab of the Block Authoring Palettes. Then add a Lookup action from the Action tab.
Caption: Dynamic block with Lookup parameter and action pair.
The Property Lookup Table dialog box displays. Select the Add Properties button, select the parameter you want to work with, and click on OK to return to the Property Lookup Table dialog box.
Click on the first row of the Input Properties window. If you already created a value set, select the pull-down arrow that appears and choose the first value. Otherwise, just type in your values in each row. On the Lookup Properties side of the window, enter the label you want to associate with each value.
Caption: Dynamic block lookup table.
Click on the lower right cell in the dialog box, which says Read-only by default. Select Allow Reverse Lookup.
Note: This will work only when all rows in the table are unique. It allows you to select a value from a pull-down list when you insert the block.
Click on OK, save the block, and close the Block Editor.
When you insert the block and select it to make its dynamic grips appear, one such grip will be a down arrow. Click the arrow to choose a label and its corresponding value from the list.
Caption: Select the Lookup grip (down arrow) to select a value from your lookup table.