A1 it is a description of the quality of the person or property which is in the best ever condition.
In marine insurance, before the vessel being insured, it need to undergo inspection to check its condition. A is given and it will be shown in the Llyod’s Register if the vessel is maintained in a good and efficient conditions.
Number 1 is added if the anchor mooring is in the same condition.
A1 is also considered in life assurance, where premium is based on the health status. After, medical examination, a perfectly healthy individual is given A1.