We are not 100% sure that we understand everything a display can or should do.
What is clear is that: The assessment author should be able to pick from the predefined list of display types.
We think the display type is a first step towards a UI that lets you pick a type of test/survey/quiz etc. and then sets sensible defaults. But right now its pretty confusing. It doesn't seem to make a lot of sense as to what is controled by the display type and what is a setting for a section.
We want to reorganize the display type attributes and the section functional attributes to make more sense.
Display types currently control some display attributes of an assessment section. Right now an assessment author can create a new display type which exposes confusing and complex attributes such as a chunk of adp code to display the assessment. Because it can involve ADP code we are assuming at this point that creating a new display type should be done by a site-wide admin. So we intend to restrict access in the UI to creating display types.
Right now display types to be specific to the package instance level but its not clear that is the desired behavior, however we do not have immediate plans to change it.
Display type refers to the style of display. Right now it also controls the number of questions per page. This seems wrong, Number of questions per page, is a functional attribute and should be set per section. The number of questions should not be tied to how the questions are formatted. An assessment author should be able to use any number of questions on a page with any display type.
Future thoughts: (we are not currently funded to implement these ideas)
Recently the default adp template for an assessment form has been rewritten with semantic HTML that should be suitable for most display types. The visual design can be changed with CSS. This leads me to believe that display types should evolve into CSS style declarations instead of ADP code.
Right now display types are per package isntance. In general we'd want site wide display types that can be used by any assessment author in any assessment package instance. For example, with dotlrn, each class has a seperate assessment package instance, but the display types may be resued across the whole site.