flowchart LR Start[Start: Group data by PSIPTNO + MCUST] --> Clean[Clean Data: Remove duplicates, invalid PSIFDAT, loops] Clean --> CaseCheck{How many valid records?} CaseCheck -->|1 Record| UseSingle[Use that record's PSIFDAT as Z_FRDATE] UseSingle --> End1[Done] CaseCheck -->|Multiple Records| ChainCheck{Is Chain Traversal Needed?} ChainCheck -->|Yes| Chain[Walk RT3 Supersession Chain] Chain --> ApplyRules1[Apply rules CAAAPP, NONRRS, etc] ApplyRules1 --> Best1[Pick best record by INTER > QPA > PSIFDAT] Best1 --> SetDates1[Set Z_FRDATE = PSIFDAT of best record] SetDates1 --> End2[Done] ChainCheck -->|No| PeriodCheck{Do records cover full time?} PeriodCheck -->|Yes| ApplyRules2[Apply rules to each record] ApplyRules2 --> Best2[Pick best PSIFDAT] Best2 --> SetDates2[Set Z_FRDATE = PSIFDAT] SetDates2 --> End3[Done] PeriodCheck -->|No| CaseD[Split into date ranges Case D] CaseD --> ForEachRange[For each period, apply rules] ForEachRange --> SelectPart[Select best record per period] SelectPart --> SetDates3[Set Z_FRDATE = period start] SetDates3 --> End4[Done]