Affirmative Action, in the context of race, ethnicity, etc. 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 system for categorising anyone as being a member of any racial/ethnic group in order to enact anti-discrimination laws (1 above) because anyone bringing a claim under e.g. Chapter II of the Employment Equity Act 1998 will be complaining about specific discriminatory behaviour and the nature of the behaviour (the reason why) shows the group which is the target of the behaviour and the complainant's actual or perceived membership of that group.
In order to do (2) you need some very broad conception of the particular group or groups you are targeting and, for example, the breakdown of readership of publications you might consider advertising in, but you don't need to be able to determine whether or not a specific individual is a member of the group.
However if you do (3) you appear to need a reasonably precise definition of the chosen race/ethnicity/colour/culture which can be used in the application process to determine by some objective system of assessment whether any particular applicant is or is not a member of the relevant group.
The Apartheid-era Population Registration Act 1950 established a board to conduct the process of classifying every inhabitant into one of the four categories of White, Coloured, Black or Indian and the classification process involved consideration of:
Characteristics of the person's head hair
Characteristics of the person's other hair
Area where the person lives, the person's friends and acquaintances
Eating and drinking habits
But my assumption is that such a complex process would not be practical for the purposes of affirmative action.
At the time when the Employment Equity Act 1998 was passed virtually everybody would have known what their Apartheid-era classification had been and I assume virtually everyone else would know as well because, for example, people were only allowed to reside in houses located in the particular zones allocated to White, Coloured, Black and Indian and would not have immediately moved when Apartheid ended. Presumably this is why Chapter III of the 1998 Act could define "black people" (a designated group which affirmative action may be applied to) by saying
"black people" is a generic term which means Africans, Coloureds and Indians
without defining Africans, Coloureds or Indians.
But, 25 years on, there are many people in the workforce who have never been classified under the Apartheid-era system. So, with (3) primarily in mind, my question is:
Can anyone give any examples, in any affirmative action programme that they know of, of what system was used to determine whether particular individuals were or were not members of the target group?