Editing Property Specification Language (section)

===Layers===
PSL is defined in 4 layers: the ''Boolean layer'', the ''temporal layer'', the ''modeling layer'' and the ''verification layer''.
*The ''Boolean layer'' is used for describing a current state of the design and is phrased using one of the above-mentioned HDLs.
*The ''temporal layer'' consists of the temporal operators used to describe scenarios that span over time (possibly over an unbounded number of time units).
*The ''modeling layer'' can be used to describe auxiliary state machines in a procedural manner.
*The ''verification layer'' consists of directives to a verification tool (for instance to ''assert'' that a given property is correct or to ''assume'' that a certain set of properties is correct when verifying another set of  properties).