Final answer:
Changes to Manuals or Publications not included in the Directives Issuance System are considered c) informal instructions, similar to how informal amendments to the Constitution affect interpretation without changing the written document.
Step-by-step explanation:
When changes to Manuals or Publications are not included in the Directives Issuance System, they are generally not considered formal or permanent changes. Instead, these modifications can be equated to informal instructions or guidelines that affect how the procedures or policies are to be understood or implemented, rather than altering the actual written directives. This concept is somewhat analogous to the way informal amendments work in the context of the U.S. Constitution, where the interpretation of the document changes without any alterations to the written words of the Constitution itself. Informal amendments to the Constitution can occur through various processes, such as judicial interpretations, social and cultural shifts, or changes in political practice, but they do not involve altering the actual text.