Simply put, the functionality provided by Specware consists in the capability to construct specs, morphisms, diagrams, code, proofs, and other entities. All these entities are collectively called units.
Some of the operations made available by Specware to construct units are fairly sophisticated. Examples are colimits, extraction of proof obligations, discharging of proof obligations by means of external theorem provers, and code generation.
The Metaslang language is the vehicle to construct units. The language has syntax to express all the unit-constructing operations that Specware provides. The user defines units in Metaslang, writing the definitions in .sw files (this file extension comes from the first and fifth letter of "Specware").
Currently, the only way to construct units in Specware is by writing text in Metaslang. Future versions of Specware will include the ability to construct units by other means. For instance, instead of listing the nodes and edges of a diagram in text, it will be possible to draw the diagram on the screen.