This field specifies second value in the ITU-T 14-bit international signal transfer point code pair and should not be used if the 24-bit signal transfer point code pair has already been specified.
该字段指定itu - T 14位国际信令传输点编码对中的第二位数且如果已经指定了24位信令传输点编码对就不能使用该字段。