I2 Analyst's Notebook 7 User Guide - ISS Africa -Investigation ...

Appendix B: The i2 Semantic Approach
• Naming custom link semantic types
There is also a convention for naming custom link semantic types. Use short
statements that can be read along with the entity types at the end of the links.
For example, naming a custom link semantic type Associate Of allows you to
read the entity-link-entity combination as Person A associate of Person B.
Avoid using the entity type names at the end of a link as part of the link type
name. For example, avoid giving a link type that links a person to a vehicle the
name Person-Vehicle. Instead use a name such as Is Registered Keeper Of, or
Is Driver Of. Notice again the use of a verb to indicate that a link is directional,
that is a person entity is the driver of a car and not vice versa. Symmetric (that
is non-directional) links will not need a verb but should still be assigned a
sensible name.
• Property semantic types must be unique within an entity, link or data record
You can only assign a property semantic type once within a given entity, link or
data record. There are instances when you may want to assign the same
semantic type to two or more properties within an entity, for example multiple
aliases or multiple forename properties. In these cases, we advise you to
define custom semantic types for these properties with _1, _2, _3, and so on,
appended for each custom semantic type beyond the first. In some
circumstances, the power2 products automatically define custom semantic
types to avoid duplicating the semantic type names; in this instance they use
this same naming convention.
Sharing custom semantic types
There is a mechanism within power2 products that allows you to share custom
semantic types between data sources. If you are using multiple data sources, it is
vital that you use this mechanism in order for semantics to work correctly.
You share custom semantic types by exporting them to a custom semantic type
library in the form of an .mtc file.
This file can be loaded into other data sources so that the same custom semantic
types can be assigned across all of the different data sources. This is the only way
to use the same semantic types; it is not enough to just define a new type in your
second data source and assign it the same name. Although their names will be the
same, their unique identifiers will be different when the two data sources are
combined. The end result will be a duplicate semantic type and the data cannot be
aligned.
For example, when assigning semantic types to data source A, you may find that
you need to derive a custom semantic type for people giving evidence. You define
a custom semantic type called Witness derived from the Person semantic type.
You then move on to data source B and find that you also need the same Witness
custom semantic type. If you define a new custom semantic type in the data
364 i2 Analyst’s Notebook 7 User Guide: Customizing & Analyzing