A further way to modify invoice templates is to alter the font size and formatting.  From the 'Print Settings' page you can press the 'Advanced Settings' button where you are able to enter/change various font attributes:

This screen shows that IDs 1 - 5 have been added and that the individual font settings have been made.  Onyx supports IDs 1 to 6 within all invoice templates, however, the more adventurous may add additional IDs and add code to the templates so that other areas of the templates can be modified (please ask for further details if you would like to investigate this yourself).  The following image details which ID affects which area of the invoice:

1 Header Labels - Red

2 Qty - Black

3 Part No - Blue

4 Rest of invoice row details - Brown

5 Invoice comments - Grey

6 Totals - Yellow

So, if you would like an invoice to list all the items in uppercase, simply add IDs 2,3,4 and set the formatting for each to 'Upper case'