UNIT-SPEC-DEFN ::= unit-spec-defn UNIT-SPEC-NAME UNIT-SPEC UNIT-SPEC ::= UNIT-SPEC-NAME | UNIT-TYPE | ARCH-SPEC
A unit specification definition UNIT-SPEC-DEFN is written:
where the terminating `end' keyword is optional.
- unit spec
- USN =
- USP
- end
It provides a name USN for a unit specification US, which is either a unit type, or the name of another unit specification, or an architectural specification (either a reference to the defined name of architectural specification, or an anonymous architectural specification).
It defines the name USN to refer to the unit specification USP, extending the global environment (which must not already include a definition for USN). The local environment given to USP is empty.
UNIT-SPEC-NAME ::= SIMPLE-ID
An unit specification name UNIT-SPEC-NAME is normally displayed in a SMALL-CAPS font, and input in mixed upper and lower case.
A reference in a unit specification UNIT-SPEC to a unit specification named USN is simply written as the name itself. It refers to the the current global environment, and is well-formed only when the global environment includes a unit specification definition for USN. The enclosing definition then merely introduces a synonym for a previously-defined unit specification.