egXML (feature system declaration) provides a feature system declaration comprising one or more feature structure declarations or feature structure declaration links. (feature structure declaration) declares one type of feature structure. gives a name for the type of feature structure being declared. gives the name of one or more typed feature structures from which this type inherits feature specifications and constraints; if this type includes a feature specification with the same name as that of any of those specified by this attribute, or if more than one specification of the same name is inherited, then the set of possible values is defined by unification. Similarly, the set of constraints applicable is derived by combining those specified explicitly within this element with those implied by the baseTypes attribute. When no baseTypes attribute is specified, no feature specification or constraint is inherited. (feature system description (in FSD)) describes in prose what is represented by the type of feature structure declared in the enclosing fsDecl. (feature structure declaration link) associates the name of a typed feature structure with a feature structure declaration for it. identifies the type of feature structure to be documented; this will be the value of the type attribute on at least one feature structure. supplies a pointer to a feature structure declaration (fsDecl) element within the current document or elsewhere. (feature declaration) declares a single feature, specifying its name, organization, range of allowed values, and optionally its default value. indicates the name of the feature being declared; matches the name attribute of f elements in the text. indicates whether or not the value of this feature may be present. (feature description (in FSD)) describes in prose what is represented by the feature being declared and its values. (value range) defines the range of allowed values for a feature, in the form of an fs, vAlt, or primitive value; for the value of an f to be valid, it must be subsumed by the specified range; if the f contains multiple values (as sanctioned by the org attribute), then each value must be subsumed by the vRange. (value default) declares the default value to be supplied when a feature structure does not contain an instance of f for this name; if unconditional, it is specified as one (or, depending on the value of the org attribute of the enclosing fDecl) more fs elements or primitive values; if conditional, it is specified as one or more if elements; if no default is specified, or no condition matches, the value none is assumed. defines a conditional default value for a feature; the condition is specified as a feature structure, and is met if it subsumes the feature structure in the text for which a default value is sought. separates the condition from the default in an if, or the antecedent and the consequent in a cond element. (feature-structure constraints) specifies constraints on the content of valid feature structures. (conditional feature-structure constraint) defines a conditional feature-structure constraint; the consequent and the antecedent are specified as feature structures or feature-structure collections; the constraint is satisfied if both the antecedent and the consequent subsume a given feature structure, or if the antecedent does not. (bi-conditional feature-structure constraint) defines a biconditional feature-structure constraint; both consequent and antecedent are specified as feature structures or groups of feature structures; the constraint is satisfied if both subsume a given feature structure, or if both do not. (if and only if) separates the condition from the consequence in a bicond element. (feature structure) represents a feature structure, that is, a collection of feature-value pairs organized as a structural unit. specifies the type of the feature structure. (features) references the feature-value specifications making up this feature structure. (feature) represents a feature value specification, that is, the association of a name with a value of any of several different types. A feature value cannot contain both text and element content A feature value can contain only one child element provides a name for the feature. (feature value) references any element which can be used to represent the value of a feature. (binary value) represents the value part of a feature-value specification which can contain either of exactly two possible values. supplies a binary value. (symbolic value) represents the value part of a feature-value specification which contains one of a finite list of symbols. supplies the symbolic value for the feature, one of a finite list that may be specified in a feature declaration. (\p{L}|\p{N}|\p{P}|\p{S})+ (numeric value) represents the value part of a feature-value specification which contains a numeric value or range. supplies a lower bound for the numeric value represented, and also (if max is not supplied) its upper bound. (\-?[\d]+/\-?[\d]+) supplies an upper bound for the numeric value represented. (\-?[\d]+/\-?[\d]+) specifies whether the value represented should be truncated to give an integer value. (string value) represents the value part of a feature-value specification which contains a string. (value label) represents the value part of a feature-value specification which appears at more than one point in a feature structure. supplies a name for the sharing point. (\p{L}|\p{N}|\p{P}|\p{S})+ (collection of values) represents the value part of a feature-value specification which contains multiple values organized as a set, bag, or list. (organization) indicates organization of given value or values as set, bag or list. set indicates that the given values are organized as a set. bag indicates that the given values are organized as a bag (multiset). list indicates that the given values are organized as a list. (default feature value) represents the value part of a feature-value specification which contains a defaulted value. (value alternation) represents the value part of a feature-value specification which contains a set of values, only one of which can be valid. (value negation) represents a feature value which is the negation of its content. (merged collection of values) represents a feature value which is the result of merging together the feature values contained by its children, using the organization specified by the org attribute. indicates the organization of the resulting merged values as set, bag or list. set indicates that the resulting values are organized as a set. bag indicates that the resulting values are organized as a bag (multiset). list indicates that the resulting values are organized as a list. (feature library) assembles a library of feature elements. (feature-value library) assembles a library of reusable feature value elements (including complete feature structures).