When setting system variables within the <PARAMETERS> section of a Precondition, using a system variable will fail.
1.) Create a workflow with a test job in it.
2.) On the job's task properties add an 'Execute Object' precondition.
3.) Create a SCRI object with a prompt to be executed by the precondition defined in step 2.
4.) Add the SCRI object to the precondition and edit the <PARAMETERS> section.
5.) Add a system variable to the <PARAMETERS>. For example, &$AGENT#
6.) Execute the workflow. You will see:
U00021719 Syntax error in object '*', line '00000'. 'U01001308 Variable '$AGENT#' has not yet been defined.'.