On Sat, 3 Nov 2007 12:00:32 +0000, Andy Hall
wrote:

The answer lies with catalogue number 88345 which is a replacement cartridge.

As suspected, it's a polyphosphate dosing system. Scale reduction,
yes. Softening, no.

Sorry if I got the terminology incorrect? As you've already found out,
the replacement cartridge says it contains phosphate so I assumed that
the phosphate ions were exchanged with the sodium/chloride ones.