Data Specification on Orthoimagery – Draft ... - INSPIRE - Europa

INSPIRE Reference: D2.8.II.3_v2.0
TWG-OI <strong>Data</strong> <strong>Specification</strong> on Orthoimagery 2011-06-15 Page 6
version Association
role
5.1.2 Placeholder and candidate types
If in an application schema an association role ends at a spatial
object type, this stereotype denotes that the value of the property is
meant to be a specific version of the spatial object, not the spatial
object in general.
Some of the INSPIRE Annex I data specifications (which were developed previously to the current
Annex II+III data specifications) refer to types that thematically belong and were expected to be fully
specified in Annex II or III spatial data themes. Two kinds of such types were distinguished:
− Placeholder types were created as placeholders for types (typically spatial object types) that
were to be specified as part of a future spatial data theme, but which was already used as a
value type of an attribute or association role in this data specification.
Placeholder types received the stereotype «placeholder» and were placed in the application
schema package of the future spatial data theme where they thematically belong. For each
placeholder, a definition was specified based on the requirements of the Annex I theme. The
Annex II+III TWGs were required to take into account these definitions in the specification work
of the Annex II or III theme.
If necessary, the attributes or association roles in the Annex I data specification(s) that have a
placeholder as a value type shall be updated if necessary.
− Candidate types were types (typically spatial object types) for which already a preliminary
specification was given in the Annex I data specification. Candidate types did not receive a
specific stereotype and were placed in the application schema package of the future spatial
data theme where they thematically belong. For each candidate type, a definition and attributes
and association roles were specified based on the requirements of the Annex I theme. The
Annex II+III TWGs were required to take into account these specifications in the specification
work of the Annex II or III theme.
If the type could not be incorporated in the Annex II or III data specification according to its
preliminary specification, it should be moved into the application schema of the Annex I theme
where it had first been specified. In this case, the attributes or association roles in the Annex I
data specification(s) that have the type as a value type shall be updated if necessary.
Open issue 1: For all Annex II+III themes for which placeholders and candidate types were specified
in an Annex I data specification, it should be clearly indicated in the data specification, how the
placeholder and candidate types were taken into account. If the proposed solution would require any
changes to an Annex I data specification (and the corresponding section in the IR for interoperability of
spatial data sets and services), this should also be clearly indicated.
A thorough investigation of the implications of the proposed changes of candidate types (in particular
related to requirements of Annex I maintenance) will have to be performed for v3.0 of the data
specifications.
5.1.3 Voidable characteristics
If a characteristic of a spatial object is not present in the spatial data set, but may be present or
applicable in the real world, the property shall receive this stereotype.
If and only if a property receives this stereotype, the value of void may be used as a value of the
property. A void value shall imply that no corresponding value is contained in the spatial data set
maintained by the data provider or no corresponding value can be derived from existing values at
reasonable costs, even though the characteristic may be present or applicable in the real world.