Diminishing notional capital rules-is CTR not received an allowable deduction

Have just posted the following question re clients on PC, but the same question applies to IS etc
Diminishing notional capital [DNC] applies to my client. PC and HB not received have been taken into account under DNC rules, but seemingly not CTR.
SPCRegs 2002 Reg 22 para (3) (c) refers to CTB (not CTR) to be taken into account as a deduction.
The same wording applies under the IS Regs, Reg 51A.. There seems to have been no change of definition of CTB to include CTR for DNC.
Has anyone come across this and does PC/IS take CTR into account as a relevant deduction in DNC rules treating CTB also as including CTR?