A characteristic of a material, process, or measurement. Attributes can be a GEMD property, condition, or parameter and contain a value.

Attribute Template

Attribute templates define a domain concept (e.g. density, yield strength), and include bounds to define acceptable values for a given attribute.


Bounds are used in object and attribute templates. An attribute template will have the widest bounds, and an object template can restrict them. For example, the temperatures in casting will always be higher than the temperatures for annealing. Each value type (e.g., real, categorical) has a corresponding type of bounds.

Categorical Bounds

Bounds that are defined by a list of categories.

Condition Attribute

Environmental variables (typically measured) that may affect a process or measurement, such as temperature or pressure.

Data Object

GEMD materials, processes, measurements, and ingredients. Data objects along with attributes are linked to form a complete description of a final material and how it was created.


Graphical Expression of Materials Data, an open source format for storing materials data.

Ingredient Object

A data object that annotates a material with information related to its usage in a process. Ingredient objects are used define how much of a material is used in a new process. Note that 'ingredient' and 'material' object definitions are not interchangeable.

Material Object

GEMD data object that describes a physical substance that is generated by a process and is characterized by its properties. GEMD does not allow material objects to exist in isolation, since fully describing a material data point requires, at minimum, identifying how the material was procured.

Material Run

An actual instance of a material.

Material Spec

Material spec objects are used to integrate information from external references, typically a data sheet. Reference information is optionally encoded via PropertyAndCondition attributes.

Material Template

Define how to validate any PropertyAndConditions attributes, if they exist on a linked material spec.

Measurement Object

A data object used to describe an operation that measures or characterizes properties of a material.

Measurement Run

A recorded measurement for a specific material run object.

Measurement Spec

Defines the experimental design or standard operating procedure for a measurement, including any parameters and conditions.

Measurement Template

Defines which conditions, parameters and properties are expected for a class of experimental measurements.

Nominal Real Value

A value type in which the value is recorded as a specific number with a unit, with no information about the uncertainty of that number.

Object Template

Object Templates define a domain concept for a process, material or measurement. Object templates compose bounds from attribute templates into constraints that define valid ranges.

Parameter Attribute

Describes the settings of a tool in a process or measurement object. Parameters are non-environmental variables (typically specified and controlled) that may affect a process or measurement.


Portable Information Format, a precursor to GEMD that is no longer in use.

Process Object

GEMD data object that describes an operation to generate an output material from inputs.

Process Run

A recorded run of a process, which may include parameters that are controlled and/or measured.

Process Spec

Defines the intent for how a process should work, including any expected parameters and conditions.

Process Template

Process templates are used to define constraints for the names and labels of ingredients. They may link conditions and parameters.

Property Attribute

Describes a measured or calculated property of a material object.

PropertyAndConditions Attribute

Known (unmeasured) properties of a Material Spec, with specified conditions. These usually come from a technical spec sheet or other external reference.

Real Bounds

Bounds defined by a range of finite real values and a unit.


Template, spec and run. Data objects are created in a state, representing generalization (template), intent (spec), and actual result (run).


Tags are used to categorize object templates.

Uniform Real Value

A value type in which the value is recorded as a range, with a lower bound and an upper bound, to represent the uncertainty of the measurement.