The System attribute group 'Storyspace' accommodates interchange use of Storyspace v3 files. For more on the inter-relation of Tinderbox and Tinderbox see Tinderbox's pre-history.
The Storyspace product page; http://www.eastgate.com/storyspace/.
Storyspace Guard Fields
In Storyspace a basic or text link may, optionally, include a 'guard field'. This is condition, written as an action code expression that must be met before the user may follow the link.
Tinderbox files will store Guard field data but cannot use it—or read it.
See also—notes linking to here: