The specific here is one very odd symptom or a name someone has applied to a range of types of symptoms. It can be used therapeutically. It can also be used when a particular symptom is so unique as to lead unmistakably to a remedy.
Using a small rubric (one with few remedies) in Kent's repertory is not recommended unless it is very clear. It is much better to use a larger rubric to gather more possible remedies which will show the remedy picture more consistently.
This is unfortunately how people select a remedy from the drug store counter and is one of the more useless forms of homeopathic remedy selection.