This is a model code. In the Vladmodels taxonomy, letters often denoted a series or a photographer, while numbers identified the model. "Y" likely refers to a specific shooting cycle or sub-studio. "107" is the model’s internal ID. In fan forums, model 107 (Karina) was known for a specific look: typically slim, dark-haired, with a reserved expression that contrasted with the more overtly performative models in the catalog.