Currently the reference collector when creating a UDF only allows for one reference to be selected. But some of the more advanced features can require multiple references. An example of this is the Offset Tool to offset an edge or surface. Sometimes it is necessary to select multiple surfaces such as both halves of an outer diameter to create a reference set. Currently if the Offset Tool is used in a UDF there is a chance that feature will fail when placed or it will not function as intended.