Affirmative Action, in the context of race/ethnicity, can cover a variety of measures such as
simple non-discrimination (depending on definitions this might not be classed as "affirmative action" at all)
targeting job advertisements at particular groups
actually favouring target groups in the process of considering applications.
You don't need to have any predefined racial categorisations in order to do (1) because you can have an anti-discrimination law without having legally defined race categories. Anyone bringing a discrimination claim has to show they they are of a identifiable race/ethnicity and that they were unfavourably treated by a named individual (or organisation) because of that race/ethnicity. But the race/ethnicity is identified by the individual complainant in the individual case. There is no need for a predefined list of races/ethnicities.
In order to do (2) you need some very broad conception of the particular group or groups you are targeting but you don't need an actual definition.
However if you do (3) you need a reasonably precise definition of the race/ethnicity which the application process is to favour so that those administering the application process handle applications in the intended way. My question primarily has (3) in mind and is:
Can anyone give any examples of how the relevant race/ethnicity is /was defined in an affirmative action programme that they know of?