The rate codes for the 5K points package vary, depending on whether it's a locally-sourced 5K package (ie the hotel does it manually) or whether it's an IHG-sourced package (ie the rate is a bog-standard 5K per stay rate, selected as per my earlier screenshot). They also depend on the area - when I stay at my favourite haunt the invoice says "5000 RC EMEA", ie the rate code (whatever it may be) only applies in Europe, the Middle East and Africa.

You can get a list of the bonus point rate codes easily enough, as it's contained in the URL when you search on IHG's site for bonus point packages. They are as follows:

IKPT5.IKP50.IKPT3.IDSOR.IKP10.IKPC2.IKPC3.IKPC4.IJ BPC.IKCV3.IKPCB.IKPCA.IKBB5.IKCV7.IKHB4.IKHB2.IKPC 9.IKPC8.IKPC7.IKPC6.IKPC5.IKPCT.IKICB.IKPCP.ISSEP. IKPCM.IJBPS.IKBB1.IKAM2.IKAM4

It's highly likely the 5K-per-stay bonuses will have a 5 in the name - so IKPT5, IKP50, IKBB5, IKPC5.

EDIT: And looking at the source code that appears when you "change rate" on a forthcoming stay booked in the UK at the "5K per stay" rate.....

input id="rateCategory" name="rateCategory" type="hidden" value="IKP50"

There you go - it's IKP50 for the EMEA 5K rate.