Gadgetbridge/app/src/main/res/xml/devicesettings_reserve_alarms_calendar.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.preference.PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">

    <EditTextPreference
        android:icon="@drawable/ic_access_alarms"
        android:defaultValue="0"
        android:digits="0123"
        android:inputType="number"
        android:key="reserve_alarms_calendar"
        android:maxLength="1"
        android:title="@string/miband_prefs_reserve_alarm_calendar" />

</androidx.preference.PreferenceScreen>