[caret-users] Q) fiducial surface in '711-2C' space?

[Yune S. Lee]

 Dear Caret users,

 i'm a novice for caret and wondering what fiducial surface in '711-2C' 
space is about.
 Can anyone explain what this space is about (e.g., what does 711-2C mean?)

 thanks,
 YSL