The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it is written from left to right. When changing direction it is not mirrored. The word that U+03C2 forms with similar adjacent characters prevents a line break inside it. The glyph can be confused with 6 other glyphs.
The Wikipedia has the following information about this codepoint:
Sigma ( SIG-mə; uppercase Σ, lowercase σ, lowercase in word-final position ς; Greek: σίγμα) is the eighteenth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 200. In general mathematics, uppercase Σ is used as an operator for summation. When used at the end of a letter-case word (one that does not use all caps), the final form (ς) is used. In Ὀδυσσεύς (Odysseus), for example, the two lowercase sigmas (σ) in the center of the name are distinct from the word-final sigma (ς) at the end. The Latin letter S derives from sigma while the Cyrillic letter Es derives from a lunate form of this letter.
Representations
System
Representation
Nº
962
UTF-8
CF 82
UTF-16
03 C2
UTF-32
00 00 03 C2
URL-Quoted
%CF%82
HTML hex reference
ς
Wrong windows-1252 Mojibake
Ï‚
HTML named entity
ς
HTML named entity
ς
HTML named entity
ς
alias
stigma (the Modern Greek name for this letterform)