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Data Set context and Temporality aspects

Data Set context and Temporality aspects

Owned by POROSNICU Eduard
Last updated: 2025 Mar 11

Introduction

The AIXM Business Rules are used to validate data contained in AIXM Data Sets. In a Data Set, an AIXM feature instance may be present with one or more TimeSlices, with different interpretation value ('BASELINE', 'TEMPDELTA', 'PERMDELTA', 'SNAPSHOT').

TimeSlice interpretation

It shall be kept in mind that all AIXM data sets apply a Temporality Concept based on 'TimeSlices'.  The UML class diagrams that document the AIXM data structure do not display directly this temporal aspect of the data structure. Instead, each AIXM class has a stereotype that indicates how it is positioned from a temporal point of view:

  • classes with <<feature>> stereotype exist on their own as instances and have "timeslices"
  • classes with  other stereotypes (mainly <<object>>) do not exist on their own as instances. They are always in a composition relationship with another class. They do not have timeslices anywhere in their descendant structure.

The two UML class diagrams below explain this difference. On the left side, it is a diagram from the AIXM UML model, as published. On the right side, this UML class diagram example is expanded with the "TimeSlice" concept. The meaning of the TimeSlice, interpretation, sequenceNumber, etc. is explained in the AIXM Temporality Concept document.

AirportHeliport - Runway (non-temporal)AirportHeliport - Runway using the TimeSlice concept

The following XML example highlights the location of the TimeSlice nodes in the AIXM XML file structure. 

Important Note

An AIXM feature, such as Runway may have several timeslices. In an AIXM data set, these may exist as children of the same or of different parent <Runway> elements. In case the timeslices appear in different Runway elements, these Runway elements will have the same gml:identifier. 

If necessary for facilitating the execution of the AIXM business rules, an AIXM data set could be normalised - all TimeSlices of a feature to appear as child elements of the same feature element.



From the TimeSlice interpretation point of view, each AIXM rule belongs to one of the following categories:

TimeSlice interpretation

Applicability

Example

<timeslice>Baseline</timeslice>

Rules that are applicable only to TimeSlices with interpretation equal-to 'BASELINE'.

  • rules that verify the completeness of the data, in relation with the ICAO AIP data set specifications
  • rules that verify the presence of required data quality attributes
  • etc.
<timeslice>All</timeslice>Rules that are applicable to any TimeSlice (any interpretation value). If applicable, the rule definition itself might test the value of the timeSlice.interpretation in one of its elementary conditions.
  • rules that require a specified unit of measurement to exist for each numerical value where this is applicable
  • rules that verify the consistency of the coding with a specific Digital NOTAM scenario
  • etc.

Validation context

The definition of a rule may involve properties that appear inside a single TimeSlice, properties that appear in two TimeSlice of the same feature instance or properties that appear in TimeSlices of different feature instances.

Note

The term "feature instance" covers both features of different kinds and features of the same kind, but which have a different gml:identifier. For example, two distinct DesignatedPoint (different gml:identifier) are considered different "feature instances".

From this point of view, each AIXM Business Rule belongs to one of the following categories:

ContextApplicabilityExampleData verification points

Single TimeSlice

<context>TS</context>

Rules of this kind verify the data present inside a single TimeSlice, of a single Feature Instance.

This includes rules that are expressed for convenience at the ::dataSet level, but for which the verification remains local (on a single property, inside one TimeSlice).

It is prohibited that MarkerBeaconTimeSlice has frequency@uom value other-than 'MHZ'

It is prohibited that ::dataSet has-descendant gml:pos value contains-substring 'NaN'

The values of the properties included in the TimeSlice are verified without taking into consideration a specific point in the timeline. For alignment with the other cases, it can be considered that the verification is done at the start of validity of the TimeSlice.

Two TimeSlice, same Feature instance

<context>FT</context>

Rules of this kind verify the data present in two TimeSlices of the same FeatureInstance. These TimeSlices may have different interpretations.

Typical examples are rules that validate 

  • two consecutive BASELINE TimeSlices, or
  • a TEMPDELTA TimeSlice versus a BASELINE TimeSlice that has an intersecting validity period
It is prohibited that Runway has timeSlice[1] 
and timeSlice[1] has RunwayTimeSlice.type value as 'RWY' 
and Runway has timeSlice[2] 
and timeSlice[2] has RunwayTimeSlice.type value other-than 'RWY'

There are two possible situations:

a) Two BASELINE TimeSlice of the same Feature instance.

The verification needs to be performed at the touch-point on the timeline of each consecutive two timeslices.

b) One BASELINE and one TEMPDELTA Timeslice of the same Feature instance, that have a partially overlapping time validity:

The verification needs to be performed at the start of validity of each TimeSlice that intersect the validity of another TimeSlice

Data Set

<context>DS</context>

Rules of this kind verify the data present TimeSlice of two or more different Feature instance, which are part of the same data set. A single TimeSlices is involved from each Feature.

It is prohibited that RunwayTimeSlice has type value as 'RWY' 
and RunwayTimeSlice.associatedAirportHeliport@xlink:href references-to AirportHeliport 
and AirportHeliport has timeSlice.AirportHeliportTimeSlice.type  value as 'HP'


It is prohibited that event:Event has event:timeSlice.event:
EventTimeSlice.event:scenario value as 'AD.CLS'  and event:Event has event:timeSlice.
event:EventTimeSlice.event:version value as '2.0'  and not  event:Event is-referenced-by AirportHeliportTimeSlice.extension.
event:AirportHeliportExtension.event:theEvent@xlink:href

The verification needs to be performed at the start of validity of each TimeSlice that intersect the validity of another TimeSlice

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