I'm running into issues where I can successfully generate a display for one SFC, and another fails.  The failure message I'm getting is "...could not be built due to the following error: UnexpectedError".  I have been comparing the successful SFC FHX to the unsuccessful SFC FHX to identify and systematically eliminate differences.  So far I have not been able to resolve the issue. 

Does anyone have an accurate list of the character restrictions / limitations for the SFC Visualization utility?  I'm finding that the limitations listed in the help file do not appear to be accurate.  For instance all of our SFC's have comments in expressions, confirmations, transitions, etc. Per the help file comments are not allowed (see below).  I have successfully generated displays from SFC's that comments in the "(* *)" and "REM" format.  I have also been able to generate displays from SFC's that have action descriptions with quotation marks as well.  The one limitation I'm not entirely certain of is the "Actions, transition expressions, and description text cannot contain any control characters or quotation marks."  I have been searching through the FHX to identify control characters such as TAB, but I'm wondering if there are other common characters I should be aware of.

For reference the help file limitations are as follows: