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0001 # Glossary
0002
0003 :::{glossary}
0004 EDM
0005 Event Data Model is a set of classes that can be used to describe the
0006 contents of an event.
0007
0008 Hole
0009 A hole is a state on a track where no measurement was found.
0010
0011 Outlier
0012 A measurement associated with a track, where the measurement is considered
0013 *far away* from the nominal parameter vector of the track on the associated
0014 measurement surface. This is often defined as measurement with a $\chi^2$
0015 larger than a certain threshold value.
0016
0017 SoA
0018 *Struct of Arrays* is a memory layout in which individual properties of an
0019 object are stored as contiguous arrays in a structure, where the same index
0020 is associated with logically connected entries. The opposite is {term}`AoS`.
0021
0022 AoS
0023 *Array of Structs* is a memory layout where a collection of objects are
0024 stored in a single array, where each object internally has a member for each
0025 property.
0026
0027 Seed
0028 A starting point for the track finding stage. E.g. a triplet of {term}`space
0029 points<Space point>` that are loosely compatible with a track hypothesis.
0030
0031 Space point
0032 A three dimensional (possibly approximated) location through which a particle
0033 will have passed and created masurements. In some cases, like strip
0034 detectors, space points are [formed from multiple
0035 measurements](#tracking_sp_formation).
0036 :::
