ANSI Common Lisp 2 Syntax 2.4 Standard Macro Characters 2.4.6 Backquote
220.127.116.11 Notes about Backquote
Since the exact manner in which the Lisp reader will parse
an expression involving the backquote reader macro
is not specified, an implementation is free to choose any
representation that preserves the semantics described.
Often an implementation will choose a representation that facilitates
pretty printing of the expression, so that (pprint `(a ,b)) will display
`(a ,b) and not, for example, (list 'a b). However, this is not a
Implementors who have no particular reason to make one choice or another
might wish to refer to IEEE Standard for the Scheme Programming Language, which identifies a popular choice of
representation for such expressions that might provide useful to be useful
compatibility for some user communities. There is no requirement, however,
that any conforming implementation use this particular representation.
This information is provided merely for cross-reference purposes.