An 'achievement' is a full formal display of a coat of arms. This form of display is normally used in formal situations, and can be used for decorative elements, banners, and on your scrolls. An achievement is your device surrounded by all the extra elements accorded to you by your rank in the SCA. For a list of elements allowed in Avacal please visit Avacal Heraldic Display
The Book Of Traceable Heraldic Art website also has artwork for the various components at Volume E: Achievement Elements and Volume M: Mantling, Helms & Crests