Time Scenarios unclear

Question

Hi BW Practitioners,
I need to clarify some doubts on Time Scenarios. Really hope you can help me a little or I may never understand BW.
1. Assuming we have Material [Mat] and Material Group [Mat Gp]. If  Parent Attribute is Material Group, and Child Characteristic is Material, what is the Child Attribute and what is the Parent Characteristic?
2. Are the Time Scenarios the solution or the problem situation? Eg. Scenario 1: 'Today is yesterday' says with material group as characteristic in the same dimension table as material, a change in Mat->Mat Gp assignment from values BBB->X  to BBB->Y results in all history data appearing as 'today', as if no change was made. So, is this a good thing or is this the problem? Is it bad to use mat and mat gp in the same dimension? Is it bad thing if a change in mat gp assignment is applied to all historic data, which results in reports able to show what is the correct value / assignment for mat gp (assuming the change was to correct the data)? Had to ask because the docu described scenario1 and then gave a solution to use mat gp as the navigational attribute of mat in the mat master data table. Is scenario 2 the solution to scenario 1?  
kr,
Ernesta

Answer 1

Hello Siggi,
I am very glad to receive a response from you.
Hope you don't mind, but I am really confused. I was reading the Multidimensional modeling doc. Its really comprehensive but I am confused still. Are there known typos in bw330 on the time scenarios topic?
The bw330 calls it Scenarios A-D. The doc calls it Scenarios 1-4.
I tried to map the explanations to bw330.
BW330
Modeling Doc
Scenario A: At time of Sales Order     |        Scenario 1: Today is yesterday
Scenario B: At Time of Data Request      |    Yesterday is today
Scenario C: At Any point in Time        |     Today / Yesterday
Scenario D: Comparing Existing & Unchanged Values    |     Yesterday & Today.
I like to verfiy Scenario B & Scenario 2.
For scenario B, there are 2 solutions, B1 and B2.
B1: The material says the modeling method should be using time-indep nav attr for material number. Also, the diagram shows to use P-Master Data table for Material.
The Doc says for this case, to model material group as time-dep nav attr of material. So, which is correct? Fyi, Doc is authored in year 2000. BW330 is version year 2003. I think the Doc is correct. But no one can confirm for me.
Further, Scenario B, solution B2, BW330 says model as time-independent external hierarchy of material. Doc says model the dependent attribute of  multi-dimensional model as a node attribute of an external hierarchy of your characteristic where the entire hierarchy or even the structure is time dependent. I  think Scenario B solution 2 should be using time-Dependent rather than independent as stated in Doc. Can you confirm my understanding?
For Scenario C : today / yesterday, should the master data table to model be Q or Y table?
Looking forward to getting advice from SAP experts.
best regards,
Ernesta
Message was edited by: Ernesta