Dynamic tuple expression in *REC statement

Question

Hi there,
I think I know the answer to this already, but here goes...
I need to use a tuple expression in a *REC statement (in place of the old-fashioned GET) but I want it to be dynamic, so at least one of the tuple members changes at runtime.
To use the basic example from SAP Help, but amended slightly, let's say this is the standard expression:
*XDIM_MEMBERSET P_ACCT = CE0004010,CE0652000
*WHEN P_ACCT
*IS "CE0004010"
*REC(EXPRESSION=%VALUE%/([P_ACCT].[CE0652000],[P_ACTIVITY].[LABPRD],[P_ENTITY].[E123]), P_ACCT="CE0661000")
*ENDWHENBut what if the P_ENTITY member should be dynamic, depending on the ENTITY member the user selects in the DM package? What I WANT to do is something like this:
*XDIM_MEMBERSET P_ACCT = CE0004010,CE0652000
*WHEN P_ACCT
*IS "CE0004010"
*REC(EXPRESSION=%VALUE%/([P_ACCT].[CE0652000],[P_ACTIVITY].[LABPRD],[P_ENTITY].[%ENTITY_SET%]), P_ACCT="CE0661000")
*ENDWHEN
...but it doesn't work. Is this even possible? And if so, what am I doing wrong?
Thanks very much,
Jason
PS. I'm already using a lookup to pull out a tax% in the same script, so I can't use it for this as well...

Answer 1

Some theory:
You have some scope at the script start (defined by user selection in DM prompt)
For each dimension you have variable %SOMEDIM_SET% containing initial script scope. If you change scope of some dimension using *XDIM_MEMBERSET SOMEDIM=MEM1,... you can always later restore original scope with *XDIM_MEMBERSET SOMEDIM=%SOMEDIM_SET%
WHEN/ENDWHEN will loop records with base members of the scope before WHEN. %VALUE% is a current record value.
You can use tuple references to other members in EXPRESSION=... Dimensions not defined in tuple will have the same base member as current record. In tuple you can also use parent members.
You can use LOOKUP as a replacement of FLD to get member from the property of the member in current record. LOOKUP can get data from current model or other model.
Vadim