Apple Aperture 2 - Manual (Page 499)

Chapter 17 Exporting Your Images 499
IV
To modify a name format to remove spaces:
1 Choose Aperture > Presets > File Naming.
2 In the Naming Presets dialog, select the preset name format you want to modify.
3 In the Format field, select and delete the spaces or characters between the name elements.
If you wish, you can also add spaces or characters between name elements.
4 Click OK.
Select the space
between name elements
and delete it.
Select the name format
you want to modify.