Indicates the optional VCCV capabilities of the PW template.
According to whether the control word is enabled,
the value can be ccCw(0)|ccAlert(1)|ccTtl(6)|cvLspping(4)|cvBfd(5)
or ccAlert(1)|ccTtl(6)|cvLspping(4)|cvBfd(5). The default
value is ccAlert(1)|ccTtl(6)|cvLspping(4)|cvBfd(5).