-addattr template: pers?clnt=<name|pass>&com=addattr&<attr_1>=<def_val_1>&<ftr_2>=... Order of query params is not important. Feature names must not end with '*' to be legal. descript: inserts new (attribute, default value) pairs. Must be used while initializing the personalization service For attributes that are added at a later stage, the profile of all users is updated to include them as well. If one or more attribute names already exist in DB, or if one or more attribute names are not legal names, code 401 (request error) will be returned. If the error code 401 is returned then none of the feature pairs in the request has been inserted in the DB. example : pers?clnt=name|pass&com=addattr&lang.en=0&lang.1=ENGLISH&lang.2=GREEK&gender=male returns : 200 OK, 401 (fail, request error), 501 (fail, server error) 200 OK : no response body exists.