BuyInRgltryAdvc
                Mandatory
                AcctOwnr
                Optional
                SfkpgAcct
                Mandatory
                BuyInAttrbts
                Repetition (1..n)
                Ref
                Mandatory
                BuyInStat
                Mandatory
                BuyInDfrrl
                Mandatory
                FinInstrmId
                Optional
                Qty
                Optional
                BuyInPric
                Optional
                Rate
Rate
                Choice
                Definition: Value is expressed as a rate.
Type: PercentageRate (Decimal)
Restrictions:
- FractionDigits: 10
- TotalDigits: 11
Amt
                Choice
                CshCompstnAmt
                Optional
                BuyInSttlmDt
                Optional
                SplmtryData
                Repetition (0..n)