This page describes currently proposed language for meta-descriptions. It may be updated frequently. = Relational operators = Standard relational operators apply ||Meaning || Operator || ||Less than ||< || ||Less or equal ||<= || ||Greater than ||> || ||Greater or equal||>= || ||Equal ||== || ||Different than ||!= || = Logical operators = Standard logical operators apply ||Meaning || Operator || ||And || and || ||Or || or || ||Xor || xor || ||Not || not || For events in the timeline of events, using ''and'' or ''or'' operators denotes that any ordering between these events is possible. = Arithmetic operators = Standard arithmetic operators apply and parenthesis are used for non-obvious precedence = Temporal operators = We want to be able to denote order and concurrency of events and state changes, and duration of events. ||Meaning || Operator and example || ||A occurs after B || B -> A || ||A and B occur concurrently || A | | B || ||A lasts T time || A,,T,, || ||A occurs T time after B || B ->,,T,, A ||