Experiences with match() subexpressions?

I'm looking for subexpressions of regexp-matches using GNU Awk's
third parameter of match(). For example

  data = "R=r1,R=r2,R=r3,E=e"
  match (data, /^(R=([^,]+),){2,5}E=(.+)$/, arr)

The result stored in 'arr' seems to be determined by the static
parenthesis structure, so with the pattern repetition {2,5} only
the last matched data in the subexpression (r3) seems to persist
in arr. - I suppose there's no cute way to achieve what I wanted?

Janis