- * Additional custom keys/values, that are not part of field storage
- * definition, can be passed in definitions. The most common setting, passed
- * along the ID definition, is 'alias' used by SqlBase source plugin:
+ *
+ * Additional custom keys/values that are not part of field storage
+ * definition can be added as shown below. The most common setting
+ * passed along to the ID definition is table 'alias', used by the SqlBase
+ * source plugin in order to distinguish between ambiguous column names -
+ * for example, when a SQL source query joins two tables with the same
+ * column names.