Explain the school’s policy for avatars and names.

From the text:

The school’s strictly enforced dress code required that all student avatars be human, and of the same gender and age as the student. No giant two-headed hermaphrodite demon unicorn avatars were allowed. Not on school grounds, anyway.

You could give your OASIS avatar any name you liked, as long as it was unique. Meaning you had to pick a name that hadn’t already been taken
by someone else.