Usually the programmer used are meant for programming multiple devices all devices or parts are not identical for example some parts may have 4KB FLASH ROM some may have 8KB like this there are various differences such as some are 5V programmable some are 12V programmable thus before programming the device the programmer needs to collect this info so that the device can be programmed accordingly. for example the programming voltage can be set properly 5V or 12V or whatever and some other necessary parameters can be adjusted.