This is a guideline to symptoms. NOS. If the client or individual has multiple dx's. e.g. bipolar and BPD, the client may exhibit more bipolar than BPD symptoms resulting in a different set of behaviors, such as timeliness. And a high intellect on the issues, as well as doing their own case studies, as bipolars can most times be highly functionable, with high IQs in time of mania. The examples go on and on.
If the individual is Specifically dx'd with one and only one personality disorder then the Introduction would apply.