There is another ASVAB score that's equally important, if not more so, because it is the score that determines if a person is eligible for military service. It's the Armed Forces Qualification Test score, or AFQT score. This score is calculated from only four of the nine Standard Scores on the ASVAB - Arithmetic Reasoning (AR), Mathematics Knowledge (MK), Paragraph Comprehension (PC), and Word Knowledge (WK). First, the WK and PC scores are added together, then the sum is doubled. This is known as the Verbal Expression (VE) score. The VE, MK, and AR scores are then added together, and the sum is the AFQT. This score is a straight percentile measure, expressed as a number from 1-99. The number is the percentage of people who scored lower than the test taker. For example, if a person receives an AFQT score of 63, that means that he did better on the test than 63% of the people who have taken it.
The scores from the other tests are used to determine what type of specialty you might be best suited for. These "composite" scores (also known as line scores, MOS scores, or aptitude area scores) are calculated by adding together combinations of the different sub test standard scores. These composite scores are then used to determine which different military jobs (aka Military Occupational Specialties or MOS) may be the best fit for you. Each branch of the military will have their own approach to these composite scores.
The various armed forces adopted all of those aspects in 1976. At that point in time, the test was in its written form rather than today’s more common form (computerized test format). The written form covers all of the previously mentioned areas as well, which is why both forms are still available. All-in-all that answers the question concerning the intention of the test.