Lower case
`a through `z expand to
\alpha through \zeta.
Upper case:
`D = \Delta `F = \Phi `G = \Gamma `Q = \Theta `L = \Lambda `X = \Xi `Y = \Psi `S = \Sigma `U = \Upsilon `W = \Omega
LaTeX does not support upper case for all greek alphabets.
Just like other Latex-Suite mappings, these mappings are not created using
the standard imap command. Thus you can type slowly,
correct using <BS> etc.