Slide 1

Stanford Digital Repository

Supplemental Analysis

•Apply format-specific rules

•Search for exceptions to general conditions

•Invalid or not well-formed files

•Files with specific preservation risks

(e.g., WAVE file with non-PCM encoding)

•Files with specific preservation advantages

(e.g., PDF that meets PDF-A profile)

•Identify files suitable for normalization or transformation to achieve higher policy status

•Local rules, repository-specific conditions


	The supplemental analysis phase is where the file assessment result is fine-tuned. It enables our automated workflow to assess preservation risk against format-specific rules. The analysis has two primary goals.

	The first is to examine the metadata created in the file inspection and validation process – produced by JHOVE -- to identify:
	- Invalid or not well-formed files
	- Files with format-specific preservation risks
	-Files with format-specific preservation advantages
	We apply a set of rules to search for files that are exceptions to the general conditions embodied by the format matrix. Identified files are “red-flagged” and/or their Policy Status is adjusted as necessary.

	The second goal of supplemental analysis is to identify files that are suitable candidates for preservation or normalization services, according to SDR policy. For instance, though files in Adobe Photoshop format currently carry a low format score (4), those meeting certain technical profiles can be reformatted to PNG or TIFF with little or no loss, thereby creating equivalent derivatives with an improved Policy Status. Similarly, a file in MS Word can be reformatted to plain text, creating a highly preservable derivative of its textual content.

	If the previous steps of the assessment process involve sustainability considerations that the greater digital preservation community agrees on by and large, then it is possible to see this step of the process as the place where local rules apply – where conditions particular to the local repository are in place (i.e., we don’t accept invalid files, we don’t store outdated versions of TIFFs, etc.)