newbie: m-expressions

I recently started looking at Lisp/Scheme. Once or twice I came
accross M-Expressions. From what I understood, m-expressions could be
used to define new syntax...first of all is this correct? Basically
I'd like to develop my own language with c/c++ like syntax...but I
would like to use lisp/scheme in the back. Any way, I have found no
tutorial that mentions m-expressions. Is it now obsolete? Any
pointers as to where I can find more information about it? Thanks.

-Falcon

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