SNOMED Documentation Search


 Other Documents

Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Gloss
tSNOMED CT
contains hundreds of thousands of
Gloss
tConcepts
and this rich resource is greatly expanded by use of
Gloss
tpostcoordinated expressions
. In any given situation the range of
Gloss
tConcepts
or
Gloss
texpressions
that are useful, relevant and meaningful is much more limited. This gives rise to a requirement to represent
Gloss
tconstraints
on the content or a particular field in a way that can be interpreted and applied by application software.

The simplest

Gloss
tconstraint
requirements can be met by specifying the list of valid codes. This requirement is addressed by
Gloss
tsubsets
specified using the
Gloss
tReference Set
mechanism. In some cases, it is useful to express the range of possible values 'intensionally' by specifying rules rather than by listing every member of the set (e.g. to include all
Gloss
tconcepts
that are
Gloss
tsubtypes
of a specified
Gloss
tconcept
).

The use of

Gloss
tpostcoordinated expressions
adds further dimensions to the requirement for
Gloss
tconstraints
. It may be necessary to specify whether all
Gloss
Spacetrue
tpostcoordinated
Gloss
trefinements
of
Gloss
tconcept
are permitted or whether some types of
Gloss
trefinement
are prohibited or required. It may also be necessary to specify whether a
Gloss
tpostcoordinated expression
that is equivalent to a permitted value is itself permitted.

Requirements for representing

Gloss
Spacetrue
texpression
Gloss
tconstraints
are closely related to the requirements for representing
Gloss
tquery predicates
in queries.