[elements] => array(
<tag name> => array(
[children] => array(
0 => <child name> //allowed children array
),
[child_validation_pcre_regex] => string, // The regex for validating
// the list of childs
[child_validation_dtd_regex] => string, // The DTD element declaration
[content] => string // null, #PCDATA, EMPTY or ANY
[attributes] => array(
<att name> => array(
[opts] => (array|string), // enumerated or CDATA
[defaults] => (#IMPLIED|#REQUIRED|#FIXED|value),
[fixed_value] => string // only when defaults is #FIXED
)
)
)
)
