Contents > 8 Defining Custom Design Metrics and Rules > 8.1 Definition of Metrics > 8.1.1 Projection

8.1.1 Projection

The projection is your primary workhorse. Most of the metrics you will want to define can be expressed as projections. With twelve optional attributes that can be combined in multiple ways, the projection offers you a lot of flexibility to define metrics. We'll start the description of attributes with simple ones, and then advance towards more intricate attributes.
8.1.1.1 Attribute "relation"
8.1.1.2 Attribute "relset"
8.1.1.3 Filter Attribute "target"
8.1.1.4 Filter Attributes "element" and "eltype"
8.1.1.5 Filter Attributes "condition" and "targetcondition"
8.1.1.6 Filter Attribute "scope"
8.1.1.7 Attributes "sum" and "stat"
8.1.1.8 Attribute "recurse"
8.1.1.9 Attribute "nesting"
8.1.1.10 Summary of Projection Attributes