SystemML Glossary
Absolute Identifier
A string referencing an object with respect to the Global Space. Always starts with a forward slash. By definition, these are not used in SystemML documents; they may, however, be used by SystemML client software to reference objects in an instance of a SystemML System.
Computable
Something that can be computed, or "progressed" through time. In general has two interfaces, input and output.
Default Set
The Set that is included on every interface, by default. Most Processes will not need additional Sets.
Expose
An object that exposes some internal member of the System (Process, Set or Port) as a property of the System, thus abstracting the internals of the System.
Global Space
The space within which the Root System resides. In the current specification, there is only one object in the Global Space, the Root System.
Interface
An unordered collection of named Sets, associated with a Computable.
Link
A one-way connection from an output Port to an input Port.
Parent
The immediate container of an object (for the Root System, the Global Space; for a Process, Link, or non-root System, the containing System; for a Set, the containing Process; for a Port, the containing Set).
Partial Identifier
A string referencing an object with respect to an implied root; for instance, with respect to the exposing System within the context of an Expose.
Port
An input or an output to a computable through which data can pass. Note that Ports do not have to have regular periods (or even be discrete-time!) but for now, they are both of these things in all implementations.
Process
A Computable consisting of a module that represents the information processing performed in some physical (causal) unit.
Relative Identifier
A string referencing an object with respect to its Parent. Never starts with a forward slash. Note that a Relative Identifier may need one or more prefixed chevrons to allow unambiguous interpretation.
Root System
The System that corresponds to the root tag of a SystemML document. This System resides in the Global Space; all other objects (Subsystems, Processes) reside within Systems.
Set
An unordered collection of named Ports, associated with an Interface.
Subsystem
A System contained within another System; a System that has a Parent System.
System
A Computable consisting of a collection of Processes, Links and Exposes that can be computed independently of its parent (with the caveat that some Systems require that one or more of their inputs be present for computation).