Here's what the South African ID Number is made up of:
Format:
{YYMMDD}{G}{SSS}{C}{A}{Z}
YYMMDD : Date of birth.
G : Gender. 0-4 Female; 5-9 Male.
SSS : Sequence No. for DOB/G combination.
C : Citizenship. 0 SA; 1 Other.
A : Usually 8, or 9 [can be other values]
Z : Control digit. There's a whole calculation for this last digit, based on all the preceding 12 digits.