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ISO 24610-2 1st Edition, October 1, 2011 Language resource management - Feature structures - Part 2: Feature system declaration
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Availability date: 07/13/2021
Description / Abstract:
This part of ISO 24610 provides a format to represent, store or
exchange feature structures in natural language applications, for
both annotation and production of linguistic data. It is ultimately
designed to provide a computer format to define a type hierarchy
and to declare the constraints that bear on a set of feature
specifications and operations on feature structures, thus offering
means to check the conformance of each feature structure with
regards to a reference specification. Feature structures are an
essential part of many linguistic formalisms as well as an
underlying mechanism for representing the information consumed or
produced by and for language engineering applications.
A feature system declaration (FSD) is an auxiliary file used in
conjunction with a certain type of text that makes use of fs (that
is, feature structure) elements. The FSD serves four purposes.
—It provides an encoding by which types and their
subtyping and inheritance relationships can be introduced and
defined, thus laying the basis for constructing a feature
system.
—It provides a mechanism by which the encoder can list all
of the feature names and feature values and give a prose
description as to what each represents.
—It provides a mechanism by which type constraints can be
declared, against which typed feature structures are validated
relative to a given theory stated in typed feature logic. These
constraints may involve constraints on the range of a feature's
value, constraints on which features are permitted within certain
types of feature structures, or constraints that prevent the
co-occurrence of certain feature-value pairs. The source of these
constraints is normally the empirical domain being modelled.
—It provides a mechanism by which the encoder can define
the intended interpretation of underspecified feature structures.
This involves defining default values (whether literal or computed)
for missing features.
The scheme described in this part of ISO 24610 may be used to
document any feature system, but is primarily intended for use with
the typed feature structure representation defined in ISO 24610-1.
The feature structure representations of ISO 24610-1 specify data
structures that are subject to the typing conventions and
constraints specified using ISO 24610-2. The feature structure
representations of ISO 24610-1 are also used within some of the
elements defined in ISO 24610-2.