These are quoted from Jing, which is subject to the license stated at
http://www.thaiopensource.com/relaxng/copying.html

# Validation errors
unknown_element=unknown element {0}
required_elements_missing=required elements missing
out_of_context_element=element {0} not allowed in this context
impossible_attribute_ignored=attribute {0} not allowed at this point; ignored
bad_attribute_value=bad value for attribute {0}
required_attributes_missing=required attributes missing
unfinished_element=unfinished element
text_not_allowed=text not allowed here
document_incomplete=document incompletely matched
string_not_allowed=bad character content for element
only_text_not_allowed=element cannot have content that consists only of text
schema_allows_nothing=schema does not allow anything: it is equivalent to <notAllowed/>