[sudo-users] Noob sees "boulder" in man sudoers Runas spec

[Roger Price]

Hi, please excuse an obvious noob question.  I am reading man sudoers,
and in the Runas_Spec section I see

  dgb	boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm
  The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm—but only as
  operator. E.g., $ sudo -u operator /bin/ls

What is the reference to "boulder"?  It's not mentioned anywhere else in 
the man page.  Is "boulder" the human name of user dgb?

Roger