Greek has two forms of the lower-case sigma: ς used only as the final letter of a word and the more familiar σ used everywhere else. The Unicode value of a lower-case Greek letter is the value of its upper-case counterpart plus x20. However, character entities and hexadecimal encodings allow you to represent non-ASCII symbols using only ASCII characters.) You can create an XML numeric encoding from a Unicode character by adding on the left and on the right, such as Γ for Γ, Unicode value x393. (You can simply put Unicode characters directly into your HTML page provided you set your content-type correctly. XML applications require a numeric encoding of Greek letters. HTML entities are illegal in XML and but legal in XHTML. TeX also has several variations on Greek letters that are commonly used in mathematics: \varepsilon, \vartheta, \varpi, \varrho, and \varphi. Note that the Unicode numbers above are consecutive with one exception: there is no Unicode character x3A2 between Ρ and Σ. See note below about representing Greek letters in XML. TeX also has alternate versions of some Greek letters. TeX, however, only provides symbols for Greek letters that do not look like their English counterparts. For example, the English letter “A” has Unicode value x41, but the Greek letter Alpha has Unicode value x391. HTML and Unicode distinguish between Roman letters and Greek letters that look similar. For example, in HTML, λ is &lambda and Λ is &Lambda. HTML surrounds the letter name with an ampersand and semicolon.
The letter name is capitalized to get the capitalized form.
In both systems, the code for a letter is essentially its name.
Greek letters are simple to represent in HTML and TeX.