Lisp SExpressions

Lisp SExpressions: a compact, Lisp-like alternative to XML for representing recursive data structures.

See wikipedia's page on S-expressions.

Xgram Format is an example of an S-expression subgrammar. See e.g. DartSrc:ecfg/t/newexample.eg

The S-expression output format of the CPAN module 'Data::Stag' is another example:

 '(db
	 (species_set
		(species
		  (common_name "house mouse")
		  (binomial "Mus musculus")
		  (tax_id "10090"))
		(species
		  (common_name "fruit fly")
		  (binomial "Drosophila melanogaster")
		  (tax_id "7227"))
		(species
		  (common_name "human")
		  (binomial "Homo sapiens")
		  (tax_id "9606")))
	 (gene_set
		(gene
		  (symbol "HGNC")
		  (tax_id "9606")
		  (phenotype "Hemochromatosis")
		  (phenotype "Porphyria variegata")
		  (GO_term "iron homeostasis")
		  (map
			 (cytological
				(chromosome "6")
				(band "p21.3"))))
		(gene
		  (symbol "Hfe")
		  (synonym "MR2")
		  (tax_id "10090")
		  (GO_term "integral membrane protein")))
	 (similarity_set
		(pair
		  (symbol "HGNC")
		  (symbol "Hfe"))
		(pair
		  (symbol "WNT3A")
		  (symbol "Wnt3a"))))