Drawing methods require a data source to provide the value that is being shown. Most commonly, the data source for a drawing method will be a tag’s value, but this is not the only option. You can also select page parameters. (See diagram.)

The differences between the choices are as follows:
Tag: Use the Tag Browser to select any tag whose value can be represented by this drawing method.
Parameters: The tag selection area is replaced by a parameter selection. From this control you can select any page parameter (or descendants of that page parameter) whose type has a value that can be represented by this drawing method.
