One of the things that are important to distinguish in digital preservation are analog objects and digital objects.
Analog objects are distinguished because they are not digitally born objects. From a book to a postcard, they can be analog objects. Analogical objects are also those created by electronic means and whose retransmission is electronic.
Putting several examples, a videotape in VHS or BETA, a movie in Super8 or in 35mm are analog objects. Another question will be whether later these objects are converted to a digital format.
Analog objects are distinguished by a series of properties that, once converted by the medium into a digital object, their properties change.
The digital objects can be differentiated into two types. Digital objects created from the transformation of an analog object and digitally born objects.
The fact of transforming an analog object into a digital one is the process called digitalization. In this process, properties of the analog object are often lost and other properties are acquired in the new object.
If we take as an example a digitized book, it will become several digital documents. Each page of the book, including covers and back covers, will become digital documents with a series of properties.
The book itself will no longer exist unless it is decided as preservation policy to group all digital documents into a single digital object, forming a single file.
If we take another example, in the case of a film in Super8 or 35mm format that happens to be digitally converted, this new object will become another digital one.
In this case, it could be a digital video or a whole set of loose frames that could be converted into a video using software.
In the two previous situations, single or video frames will be digital objects with a series of properties.
These properties that I am talking about continuously are the significant properties.
The digitally born objects
Another type of digital objects are those, which are born being completely digital. These are the so-called “digital born” objects. The entry of this blog, is a digital-born object.
These objects, which have their characteristic properties, are therefore much more fragile than analog objects. They have no substitute.
A digital object from a digitalization has a substitute. In case of loss it can be re-digitized, even increasing costs. An object born digital no.
You can migrate the digital object, you can change the name, you can repair them, but at no time has a substitute.
Therefore, in digital preservation, we must pay particular attention to this type of objects. They are inherently fragile.
What are the significant properties?
The significant properties of an object are those that distinguish the digital object. They are its attributes, which affect its appearance, behavior, quality and usability.
The significant properties can be grouped into five categories:
- Context (metadata)
- Appearance (color, typeface)
- Structure (Pagination, sequence of images in a video).
These significant properties have to be conserved over time, and always accessible when they are digitally preserved.
To give you an idea, I am going to describe to you, several possibilities of the significant properties of an object.
- Type of file
- Size in bytes
- The typeface
- Number of pages
- Line spacing
- Graphs inside the document
- Sequence of photographs
- Frame rate
- Mono or stereo if it’s an object with audio