pcs and unit

yon   Friday, June 11, 2004, 07:20 GMT
When you talk about shipment volume of a certain product, which one of the followings is more appropriate?

- 30,000 pcs per year
- 30,000 units (or unit?) per year

Thank you.
Someone   Friday, June 11, 2004, 07:25 GMT
30,000 units per year
yon   Monday, June 14, 2004, 01:26 GMT
So should I avoid using "pcs"? Or is it still acceptable?
Someone   Monday, June 14, 2004, 01:44 GMT

30,000 PCs or 30,000 units
yon   Monday, June 14, 2004, 02:17 GMT
The above "PCs" looks like a plural form of "PC" (personal computers). True?When I wrote "pcs" above, I used it as a shortend form of "pieces". Is this abbreviation not used commonly?
Someone   Monday, June 14, 2004, 03:45 GMT
You can use it as long as you put a period at the end. Abbreviations should have periods to show that they're abbreviations.