If you have registered no doctor data and visit the Macro page of the New Data dialog or the Edit Macro Data dialog, the Doctor field will be presented as a text entry and you need to type a doctor's name by yourself.
By contrast, if you have registered doctor data, the Doctor field will appear as radio buttons representing the registered doctor names. The default selection is the doctor that has been selected or registered most recently. Just below the radio buttons is a text entry that holds the doctor now selected. If you cannot find the doctor name you are going to insert among the radio buttons, you can type whatever you want into the entry even if it has not been registered yet. Be sure that a text to be registered in the doctor database is not the selected name of the radio buttons but the one in the text entry.
More than one doctor can share an operating system user account when executing tkDerm. In this situation, if you register these doctors' data that share an operating system account, the Doctor field will be presented with radio buttons representing these doctors when tkDerm is executed by the account.
On the contrary, a doctor can use more than an account depending on the situation. For example, you should execute tkDerm as the tkDerm superuser if you are going to do some administrative tasks including image registration and the preference setting. By contrast, it is preferable to do tkDerm as an account other than the superuser if you are going to only insert, update or search data and don't need the privilege of the superuser on the session because the superuser can do destroying actions such as deleting data and photos and might bring about an accidental data loss. In this situation, it is convenient to assign a doctor's name to two different accounts: the superuser and an account other than the superuser, thus making the same name appear in the Doctor entry when you execute tkDerm as both of these accounts.
The Operator field in Micro page of the New Data dialog or the Edit Micro dialog is equivalent to the Doctor field described above. All the explanations about the Doctor field are also applicable to the Operator field.