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

[John]

Keep in mind that for standard services the service profile will indicate if a characteristic is optional or mandatory. Optional characteristics can be omitted from a standard service if allowed. For example all of the characteristics in the Device Information Service are optional.

[endnode]

Very true. For minimal GATT Server compliant with GAP and GATT you need GAP primary service with Device Name and Appearance characteristics and GATT primary service. Things like Central Address Resolution, Preferred Peripheral Connection Parameters, Service Changed characteristics, Device Information service (with all characteristics) and many others are conditional or optional depending on other features you want to use (or specifications you want to be compliant with such as Apple Bluetooth guidelines...)