Short Form One is the foundation of all the forms in the American Kenpo system. Even though it has the least amount of moves and is the simplest to perform, it lays the foundation for each subsequent form.
Although Short Form One is the simplest form, one would be incorrect to assume that this implies that it is also the easiest form to perform. Because there are such few moves in the form, it is quite easy to spot errors, problems, physical quirks, inconsistencies, and/or misunderstood motion during the execution of this form.
Many senior instructors will ask a student newly introduced to them to perform this form for them. The purpose of this is to gauge and 'get a sense' as to the level of proficiency the practitioner has in the system. A well executed Short Form One shows a mastery of the physical and conceptual basics of the system. And, a poorly executed Short Form One shows either that the practitioner is lazy, uninformed, ill taught, or not patient enough to master such a simple form.
As a contrast - most experienced American Kenpoists will say and know that Form Four is the heart of the system for information and sophisticated execution. This is true. But, Short Form One is the most telling form of the system because it will quickly and effectively show the viewer whether the practitioner can properly execute simple basics and maneuvers.
If one were to distill this book down to its two major purposes, they would be:
1) To give the reader a single place to reference as much information about Short Form One as possible.
2) To help the reader with the information gathered to perform Short Form One as perfectly as possible.