If you look at the other records on the page there is another with the same wording for the mother's name. This usually means it was an area where the people were protesting the civil registration of their previous religious marriage. Atto #24 shows that the marriage eventually took place and this is recorded in the margin. The child's status is now legitimate. In your case you might want to get his military record and see if the mother's name is listed. If so it would imply that the parent's were married up to 20 years after his birth. My website has some articles that cover this.