#       the dotted decimal version syntax, with between 2 to 4 numbers,
    #       is supported.
    #
    if {[llength $::argv] >= 3} then {
      set version [lindex $::argv 2]

      if {[isEagle] && ![string is version -strict $version]} then {
        set pattern {^\d+\.\d+(?:\.\d+){0,2}$}

        error [appendArgs \
            "version must match regular expression: " $pattern]
      }
    } else {
      set version ""
    }