udunits/src/main/java/ucar/units/UnitFormatImpl.java
public final Unit parse(final String spec) throws NoSuchUnitException,
			UnitParseException, SpecificationException, UnitDBException,
			PrefixDBException, UnitSystemException {
		synchronized (MUTEX) {
			return parse(spec, UnitDBManager.instance());
		}
	}
public final Unit parse(final String spec) throws NoSuchUnitException,
			UnitParseException, SpecificationException, UnitDBException,
			PrefixDBException, UnitSystemException {
		synchronized (MUTEX) {
			return parse(spec, UnitDBManager.instance());
		}
	}
Parses a unit specification.  This method is thread-safe.

@param spec
The unit specification (e.g. "m/s");
@return The unit corresponding to the specification.
@throws NoSuchUnitException
A unit in the specification couldn't be found (e.g. the "m"
in the example).
@throws UnitParseException
The specification is grammatically incorrect.
@throws SpecificationException
The specification is incorrect somehow.
@throws UnitDBException
Problem with the unit database.
@throws PrefixDBException
Problem with the unit-prefix database.
@throws UnitSystemException
Problem with the system of units.