The Two Types of MDL Objects

We deal with two types of objects in MDL collections, single objects and compound objects. Regardless of the format (.jpg, .pdf, .mp3, etc.) all items in a collection will fall into one of these two categories. Knowing which type of object you are dealing with will make creating metadata easier and faster. Who doesn't like that?

Single objects are items that are composed of one and only one "digital page". It might help to think of a digital page as one scan. Good examples of single objects the would be a letter written on one side of a piece of paper or a photograph with nothing written on the back. In both cases, only the front of the item would be digitized and the resulting file would contain one scan. In the viewer only one page is visible and all of the metadata in the description box refers to the item above it. When creating metadata for single items, the metadata form should be as complete as possible for each item.

Take a look at these examples, clicking on the picture will take you to the item:

A compound object is an item that has more than one digital page or part. Books are the most obvious compound objects, but a letter written on both sides of the page or a flyer with printing on both the front and back fit in this category as well. An audio file with a transcript is another good example of a compound object. Take minute to look at some examples.

This selection of family history records from Madison County Library contains a letter and a marriage certificate.

This book from the USM deGrummond Collection has multiple pages.

You might notice some differences in the item viewer. With compound objects, the ability to select a page appears down the right hand side of the screen. The first box below the image is "Object Description" box. The object description refers to the entire compound object and any metadata that appears in this box should be applicable for every page of the object. 

The following box is labeled "Description". The description box contains the metadata specific to the page being viewed. If you select a different page of the deGrummond book you'll notice that the information in the object description stays the same but the Title, Height, Width, and File name change in the description.

There are two description boxes.

When creating metadata for compound objects, there is no need to repeat the information for each page. Only the metadata fields that change from page to page need to be filled in. 

If you are digitizing a book for example, the first line of the metadata template will contain most of the necessary information and will constantly appear in the "Object Description" box no matter what page the user is viewing. The rest of the template then, only needs a handful of items to be filled in. This can save you time especially if you are dealing with lots of pages!

The next few tutorials will focus on creating metadata. We will cover each field of the metadata template in depth and give an example for both a single object and a compound object. (Don't let the template scare you, it is really easy!)

If you have questions please ask them in the comments or contact us.

Image Credits:
"Soldier with Rifle Holding Bayonet" courtesy of Camp Van Dorn WWII Museum and the Mississippi Digital Library

"Lifetime Teacher's Certificate" courtesy of McCain Library and Archives and The University of Southern Mississippi