1. 获取元数据 ``` metaData = MetaDataServiceHelper.GetFormMetaData(ctx, billFormId) //billFormId 为单据标识 ``` 2. 获取BusinessInfo ``` var info = metaData.BusinessInfo; //metaData 为第1点获得的元数据 ``` 3. 获取单据编码字段标识 ``` var form = info.GetForm(); //info为第2点获得的数据 var baseDataNumberName = form.NumberFieldKey; ```