I don't think there is one. The disorder manifests itself differently for everyone. I am in a group for women with BPD and my "cue" characteristic is impulsivity and self-destructive behaviors, whereas for other woman in the group, it is not. Some women deal with the abdanment issue (although I do) much more heavily than I do.

Everyone ended up with the disorder differently. Everyone was raised in a different environment. Therefore, I don't believe you can place one symptom or characteristic as the "cue" for the disorder.