Beta code is a kind of standard notation for representing accented Greek in plain ASCII text.

The alphabet conversion looks like this:

A B Γ Δ E Z H Θ I K Λ M N Ξ O Π P Σ T Y Φ Χ Ψ Ω 
A B G D E Z H Q I K L M N C O P R S T U F X Y W

Also, digamma (F) is represented by V.

It is not case sensitive; the asterisk is used beforehand to indicate a letter that is capitalized. No distinction is made between final sigma and the other kind.

Accents, breathing, and other marks, which go after the vowel being modified:

For capital letters, these marks should modify the asterisk (for 'A, use */A), unless the mark is actually on the letter instead of in front of it - for Á use *A/.

Miscellaneous marks:

Sigmas:

  • S1 - medial sigma
  • S2 - final sigma (use S1 and S2 only when the rules would give you the other)
  • S3 - lunate sigma

Escape sequences are done by using a number after a sign (like the sigma signs). There are a whole lot of them and you probably won't run into them, so I'll leave them for someone else to node, but in general:

  • $ indicates use of a particular Greek font
  • & is a Roman font
  • % is various punctuation
  • " is various quotation marks
  • @ is various formatting
  • [ is various bracketing
  • < is various "quasi-brackets", different kinds of markup spanning text
  • { is nontextual markup (titles, etc.)
  • # is other symbols in text (pretty much everything).