The Kollel writes in Background to Daf 27, bullet point number 14(b) - "Simanin D'Oraisa O D'Rabanan",

>>14) [last line] SIMANIN D'ORAISA O D'RABANAN (SIMANIN)

(a) There are certain instances where the Torah requires proof of identity, for example in order to reclaim a lost object or to identify a dead man and permit his wife to remarry. There is an argument as to whether Simanin ("signs" - identifying features) are considered a valid poof (Simanin d'Oraisa) or not (Simanin Lav d'Oraisa or Simanin d'Rabanan) in these instances.

(b) The Simanin under discussion are not general signs (e.g. the color of the clothes of the deceased), nor very specific signs (e.g. the lost Get had a hole next to the third letter Alef). The former certainly is not accepted as proof, while the latter certainly is accepted (see Insights to Yevamos 120:1). The Simanin under discussion are signs that lie in between these extremes.<<

Could you please provide me with an example of a Siman that "lie in between these extremes" (i.e. general signs versus specific signs), in the context of an agent who lost a Get?

Also, given that the agent is a reputable individual (as outlined early in Gittin), its difficult for me to think of a scenario in which an agent would not know specific signs of the Get that he is delivering (i.e. name of Sofer, names of witnesses on Get, name of husband and wife, etc.). Given that its highly unlikely for an agent to come up with anything less than a specific Siman with respect to a Get he is delivering, I can't think of a scenario/context in which this Sugya applies...