A few more questions. What model is this? It will be on a small metal plate attached to the back of the machine. And what size is it(approximately)?

In any case, the +/-.0003" figure is probably pretty close for linear accuracy. Depending on the model and the date of manufacture, it may be +/-.0005". .0001" or .0002" for repeatability and .0002" on squareness. This machine is too early to have a volumetric spec.