PSL Sequences: enclosed using curly braces: SERES (Sugar Extended Regular Expression)
Sequence elements are state properties from Modelling and Boolean layers.
Core operators are (of course): disjunction, concatenation and arbitrary repetition.
As a temporal logic: interpret concatenation as a time sequencing.
Make easier to use with additional operators defined in terms of primitives:
Further repetition operators denote repeat count ranges.
Repeat counts must be compile-time constant (for today's standard/tools).