Do I need a custom 128-bit UUID if I delete one or more Characteristic from an Adopted Service

[Renix]

Do I need a custom 128-bit UUID if I delete one or more Characteristic from an Adopted Service I do not modify the remaining Characteristics

For instance: Sniffing with Master Control Panel \nRF5_SDK_13.0.0_04a0bfd\examples\ble_peripheral\ble_app_hrs\pca10040\s132\

One of the services used is Generic Access, but only three (3) of the 5 Characteristics are used. But then a Characteristic Central Address Resolution UUID 0x2AA6 shows up under the Service

Should not this then be a Custom Service, with a 128 bit UUID? Device Name UUID 0x2A00 Appearance UUID 0x2A01 Peripheral Preferred Connection Parameters UUID 0x2A04 Central Address Resolution UUID 0x2AA6

[endnode]

If these are standard Services and Characteristics defined by BT SIG Core specifications (and amendments) then it must use assigned 16-bit UUID, otherwise GATT Clients cannot understand it. Why you would define custom UUID so only your app would understand the hierarchy under its tree?

[Renix]

endnode, I understand, thanks. I do not want to use a custom UUID if I don't have to, but the example from Nordic seems to add Characteristic Central Address Resolution UUID 0x2AA6 under the Generic Access Service. So that implies that the Generic Access Service has to be a custom Service, is it not. If I use Bluetooth Developer Studio to add Characteristic Central Address Resolution UUID 0x2AA6 to the Service Generic Access UUID 0x1800, then it forces this service to be Custom Local, and assigns some higher 16-bit UUID. I assume this assigned 16-bit UUID should be added to the 128-bit Base UUID. Regards