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	AT
A occurs T time after B	B ->T A

Existential, cardinality and modal operators

We want to be able to denote how many objects or events of a given type must/may occur.

Meaning	Operator and example
Every object A	each A
Some objects A	some A
Some object A called a1	some A a1
A must occur	A
A may occur	[A]
Exactly N objects/events of type A	|A|N
At least N objects/events of type A	|A|>=N
At most N objects/events of type A	|A|<=N