That sample would work: 

POST {{databaseRootUrl}}/ExecuteCubeDrillthrough?$expand=Axes($expand=Tuples($expand=Members($select=Name))) Authorization: {{Authorization}} Content-Type: application/json { "DrillthroughProcess": { "PrologProcedure": " mdx = ' TEMPLATE : SELECT {[D1].MEMBERS} ON 0, {[D2].[<<tuple.p>>]} ON 1 FROM [C_D1D2]';\r\n ViewCreateByMDX('C_D1D2', 'tmp', mdx, 1);\r\n DRILLTHROUGHTUPLE = JSONAdd('{}', 'p', '\"D2_E1\"');", "EpilogProcedure": "ReturnViewHandle('C_D1D2', 'tmp');" } }

Hello Svetlana,

Would it be possible to showcase/demo the drill-through functionality in V12?

I read that there are templates and contexts but no idea how to apply it and set it up.

The use case could be a source cell containing an intersection of 2 hierarchies. We drill to a target cube with for instance a different hierarchy of the same dimension with the children of the selected element from the source. Or something along these lines.

In some documentation I found (but it does not give me clues on how to use it):

ReturnViewHandle
DRILLTHROUGHTUPLE

<< >> for variable interpolation
<% %> for control structures
<# #> for comments

the keyword TEMPLATE: to an expression

TEMPLATE:
SELECT {[D3].MEMBERS} ON 0
FROM [C_D1D2D3]
WHERE (
[D1].[D1].<% if tuple.D1.D1 is defined %>[<< tuple.D1.D1.Name >>]<% else
%>DefaultMember<% endif %>,
[D2].[D2].[<<tuple.D2.D2.Name>>]
)