This property defines the Decomposition Type of the Unicodes as Square Form
Characters like ㉐,㋌,㋍, etc. are listed under Square Form Decomposition Type.
286 Characters are present in Square Form Decomposition Type starting with the Unicode point U+3250 that represents the character ㉐.
Currently, as per latest version 15.0.0, Unicode supports 18 number of Decomposition Type. Here are a few examples - Canonical Decomposition,Compatibility,Enclosing Mark, etc.