Dict is a map of name/value pairs.

Versioned library module of specs and defs.

Xeto library dependency

Xeto library dependency version constraints

Xeto data specification.

SpecSlots is a map of named Specs

XetoContext is used to pass contextual state to XetoEnv operations.

Ref is used to model an entity identifier and optional display string.

Environment for the Xeto data and spec handling.