The Armour Archive

What do the diffrent letters on Chains of Estate mean?

I've seen "A" and "S" but have no idea what they mean.

"S" is generally thought to be short for a motto, though the exact motto to which it refers has been lost to time. (Theories include Saint Simplicius; the martyrs of Soissons, Saint Crespin, and Saint Crespinian, referring to the date of the Battle of Agincourt; the Countess of Salisbury; the Latin word Signum, for a badge of honor; the French word Souvenez, meaning 'remember'; the word Soverayne; Sanctus, Sanctus, Sanctus; Seneschallus; and Steward.) What it seems to generally signify is affiliation with the Lancastrians.

"A," on the other hand, stands for "Atlantia."

http://www.richard111.com/medieval_livery_collars.htm

(among other things mentioned):
• An ingenious suggestion which may bear an element of truth suggests that a flower used by Henry IV as a badge was the Forget-me-knot, known by its 14th century French name souvent vous de moy. This may perhaps appear a little too romantic even for the “age of chivalryâ€