AXAPTA - Find a table fields label value

There are two ways to find a table field's label value:

If fields label value derived from directly fields extended data type:
 
    if (curext()=="krc" && this.RBOInventItemGroupId == "")
        ret = checkfailed(strfmt("'%1' field cannot be empty!..",
            new SysDictType(extendedTypeNum(RBORetailGroupId)).label()));
If there is a special label value dedicated at table level:

    if (curext()=="krc" && this.RBOInventItemGroupId == "")
        ret = checkfailed(strfmt("'%1' field cannot be empty!..",
            new SysDictField(tablenum(WholeSalesCampaignGroup),
fieldnum(WholeSalesCampaignGroup,RBOInventItemGroupId)).label()));