--- %YAML:1.0 test: Simple In Place Substitution brief: > If you want to reuse an entire alias, only overwriting what is different you can use a << in place substitution. This is not part of the official YAML spec, but a widely implemented extension. See the following URL for details: http://yaml.org/type/merge.html yaml: | foo: &foo a: Steve b: Clark c: Brian bar: &bar <<: *foo x: Oren foo2: &foo2 a: Ballmer ding: &dong [ fi, fei, fo, fam] check: <<: - *foo - *dong isit: tested head: <<: [ *foo , *dong , *foo2 ] php: | array('foo' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian'), 'bar' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian', 'x' => 'Oren'), 'foo2' => array('a' => 'Ballmer'), 'ding' => array('fi', 'fei', 'fo', 'fam'), 'check' => array('a' => 'Steve', 'b' => 'Clark', 'c' => 'Brian', 'fi', 'fei', 'fo', 'fam', 'isit' => 'tested'), 'head' => array('a' => 'Ballmer', 'b' => 'Clark', 'c' => 'Brian', 'fi', 'fei', 'fo', 'fam'))