YTD -> PERIODIC?
Easy!
Let's assume you want to move single month containing in %TIME_SET%
Then:
//%TIME_SET%=2015.07
*DESTINATION_APP=SOMETHING_PERIODIC
*XDIM_MEMBERSET TIME=%TIME_SET%,TMVL(-1,%TIME_SET%) //2015.07,2015.06
*WHEN TIME
*IS %TIME_SET% //%TIME_SET%=2015.07
*REC(EXPRESSION=%VALUE%) //add current month
*ELSE //TMVL(-1,%TIME_SET%) = 2015.06
*REC(EXPRESSION=-%VALUE%,TIME=%TIME_SET%) //subtract prev month
*ENDWHEN
Vadim