Hello Inma,
Now that you point it out, I'm not sure what "(Macintosh)" means there either. I know that it doesn't mean that this value won't work with PC's though. I've used it myself and you can see that it is used in a lot of the LabVIEW shipping examples. In fact, if you haven't already, you might browse through the LabVIEW shipping examples under the Help menu to see if there is already a VI that you can use or at least work off of. I'll turn in a suggestion to clear up that documentation in the meantime. I hope this helps!
Russell
Applications Engineer
National Instruments
http://www.ni.com/support