In the DocBlock for the method Zend_Measure_Abstract::setValue(), the $type parameter is described as:

@param string $type OPTIONAL A Zend_Measure_Acceleration Type

I can't imagine that we want the specific "Zend_Measure_Acceleration". The $type required here is just the index into the _units array. We just want to give an example. I imagine we just need something like:

@param string $type OPTIONAL The type of the value. Ex: Zend_Measure_Acceleration::GALILEO

Similarly, the docblock for the constructor itself contains a reference to a specific type:

@param $type type - OPTIONAL a Zend_Measure_Area Type

Probably better is:

@param string $type OPTIONAL The type of the value. Ex: Zend_Measure_Area::SQUARE_METER