Taking the rule and RS as written, the following are prohibited:
- cell phones
- head phones or ear phone
- other wireless communications devices (blue tooth and wifi are communications technologies, so devices with this technology are prohibited)
- other audio or video equipment
The only electronic device allowed is an electronic scorebook. It does not say that a communications devices with a scorebook app is legal. It is still a communications device, and hence illegal.
This means that smartphones (iPhone, Driod, Blackberry, etc.) are prohibited because they are communications devices, regardless of what apps are on the device.
I'm not sure you can buy electronic scorebooks that are not also communications devices, but that would seem to be all that is legal.