/sys$common/syshlp/helplib.hlb CC, Language topics, Statements, Labeled  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Any statement can be preceded by a label prefix of the following
  form:

       identifier:

  This declares the identifier as a label.  The scope of such a
  declaration is the current function.  Labels are used only as the
  targets of goto statements.