Get to your Categories listing quickly via the Settings toggle (or click on Automate at the top of the screen)

We've made the Categories list much simpler to use.  To make categorisation rules, click on the Manage Vendors tab to the left of the screen.

Then create these rules by clicking on the appropriate vendor(s) to the left, clicking on "Add vendor rules" to the top right of the screen, selecting the categories from the drop-down menu and clicking the Add Rule button!  So yes, if more than one vendor needs the same rule, you can do this very quickly in Digit.

Alternatively, you can quickly create a rule to add a Vendor/Supplier to a Category.  

Simply go to the Manage Categories tab and click on the category.

The settings for that category will then expand to allow changes.

Choose your vendor(s) from the drop-down and press Save.