In the Flow Designer, you can use variables to pass data between BLOCKS in a Flow.

Variables have the following characteristics:

• You can use multiple variables. Each different variable is identified by its assigned name.
• Regarding variable names:
  • Variable names can contain letters (a–z, A–Z), numbers, and underscores (_).
  • You cannot name variables using only numbers.
  • BLOCKS uses predefined variables with names that start with an underscore (_). These variables are listed below, and more may be added in the future:

    Variable	Explanation
    _flow_aliases	Contains the Flow’s user-assigned ID.
    _flow_id	Contains an automatically assigned numerical identifier given to each Flow
    _flow_name	Contains the name of the Flow’s Start of Flow BLOCK.
    _board_url	Contains the Flow Designer’s URL. E.g., https://*****.magellanic-clouds.net/
    _board_id	Contains the subdomain of the Flow Designer’s URL. E.g., The ***** portion of a URL like https://*****.magellanic-clouds.net/

• Variables are only active while a Flow is running.
• Variables can be used as input or output for BLOCKS.