The letter corresponds to the model of the oboe:
* Y - Student model
* YAS - Professional model
* YSP - Custom model
The numbers indicate the production run of the oboe. For example, a Yamaha oboe with the serial number Y012345 would be the 12,345th oboe produced in the student model line.
In addition to the serial number, Yamaha oboes also have a model name engraved on the center of the upper joint. For example, a Yamaha YAS-23 oboe would be a professional model oboe from the 23rd production run.
Here is a table of Yamaha oboe models and their corresponding serial number letter:
| Model | Serial Number Letter |
|---|---|
| Student | Y |
| Professional | YAS |
| Custom | YSP |