We will find out the mapping of this Online Device ID field
Open RCM Designer - Policy Manager
Find FF Retail Activity Policy and find Online Device ID field as shown below
Take a not for the identifier
Identifiers consist of prefix and fieldId, for this particular policy rule, the prefix is FF_RET. So, the fieldId is TF_webDeviceID
Open context folder E:\ACTIMIZE\ais_server\Instances\RB\Contexts, find context according to policy type
Find fieldId=TF_webDeviceID 
Open FF_contextConfig_main.xml to find which field in database mapped to the policy field
Check mapping for which field in xml request, we can check into data mapping as follow
Means for OnlineDeviceID field