On the PC version pressing the I, O, and U keys during seed entry will replace them with 1, 0, and V respectively.
All alphanumeric characters are accepted except for 5, I, O, and U.
This prevents any achievements from being obtained on that particular run. For example, if you find a Rebirth seed on PC, you can use it on the 3DS version and it will be the same because the 3DS version only has Rebirth.