iw_first_time

System

I am porting a workflow from TeamSite 5.0 on Solaris to 5.5.2 on Windows. The .wft contains the following code:

iw_desc => [ html => '<textarea rows="4" cols="50"></textarea>',
error_msg => 'Please enter a Job Description.',
is_required => 'true',
label => 'Job Description:',
valid_input => '$iw_first_time ne "true" && $_ ne ""',
label => '',
],

I have never seen code like the valid_input before and the .wft does not define an $iw_first_time variable so I have to assume that's something provided by Interwoven, but I don't see any hits on iw_first_time in WorkflowDevelopers5.0.1Guide.pdf. I remember a problem from some time ago that when selecting "New Job", if the user entered a job description and chose from a list of templates, if there were no other mandatory fields in the instantiation form they would never see the instantiation form - it would start the workflow without giving them a chance to select an optional approver, etc. I am wondering if this could be what the above code is trying to avoid? Can anyone tell what this code is doing?