ranges over strings; a string is a sequence of zero or more Unicode scalar values represents an empty string returns a sequence of strings one for each whitespace delimited token of ranges over local names (NCNames, names without prefixes) ranges over URIs constructs an (expanded) name with URI and local name ranges over expanded names ranges over name classes asserts that name is a member of name class constructs an attribute with name and value ranges over bags (unordered collections) of attributes; a bag with a single member is considered the same as that member represents an empty bag represents the bag union of and (the number of occurrences of any member of is the sum of the number of its occurrences in and ) ranges over namespace maps; a namespace map is a mapping from namespace prefixes to URIs represents an empty namespace map ranges over sequences of parameters asserts that in the datatype library identified by URI , the string interpreted in the context of the namespace map is a legal value of datatype with parameters asserts that in the datatype library identified by URI , string interpreted in the context of the namespace map represents the same value of the datatype as the string interpreted in the context of ranges over sequences of elements and strings; a sequence with a single member is considered the same as that member asserts that the mixed sequence is normalized: it does not contain any member that is an empty string, nor does it contain two consecutive members that are both strings constructs an element with name , namespace map , attributes and mixed sequence as children ranges over elements represents the concatenation of the sequences and represents an empty sequence ranges over strings and the empty sequence; this is a subset of the range of returns an empty string if is the empty sequence and otherwise returns returns the sequence after removing any member that is a string consisting entirely of whitespace asserts that is an interleaving of and constructs a key in symbol space with datatype in the datatype library with lexical value interpreted with respect to namespace map ranges over bags of keys asserts that there are conflicting keys in the unordered collection of keys asserts that is a subset of constructs a key reference in symbol space with datatype in the datatype library with lexical value interpreted with respect to namespace map ranges over bags of key references asserts that the collection of keys has a key that satisfies every key reference in the collection of key references ranges over patterns within the start-tag of a pattern refers to the namespace map of the pattern element asserts that the element is valid with respect to the pattern constructs an empty environment ranges over sequences of definitions constructs an environment with definitions and parent environment ranges over environments asserts that in environment , local name is bound to pattern asserts that in the context of the environment and namespace map , the attributes and the sequence of elements and strings matches the pattern generating the collection of keys and key references