These models are number from 1 to 8. This is done so that you can place them on your build plate and use the resin calibration function that is available on newer printers (eg Elegoo Mars 5 Ultra). By using these number models you can easily remember where on the build plate you had the model for identifying the length of time for that exposure.
The numbers are designed to be only a couple layers high (at 0.05mm layer height). I found this as a good test for showing what the difference in layer height looks like at the top of a round, crowned surface.
Siraya Tech has a detailed page with instructions on how to interpret your prints. It and the original model can be found here: https://siraya.tech/pages/siraya-tech-test-model
The original model does not have any identifiable license attached to it. All credit goes to the original authors!
The author remixed this model.
These 8 models are number for easy identification when doing resin calibration prints.