BuyInRgltryAdvc
                Mandatory
                AcctOwnr
                Optional
                SfkpgAcct
                Mandatory
                BuyInAttrbts
                Repetition (1..n)
                Ref
                Mandatory
                BuyInStat
                Mandatory
                BuyInDfrrl
                Mandatory
                FinInstrmId
                Optional
                Qty
                Optional
                Unit
Unit
                Choice
                Definition: Quantity expressed as a number, for example, a number of shares.
Type: DecimalNumber (Decimal)
Restrictions:
- FractionDigits: 17
- TotalDigits: 18
FaceAmt
                Choice
                AmtsdVal
                Choice
                BuyInPric
                Optional
                CshCompstnAmt
                Optional
                BuyInSttlmDt
                Optional
                SplmtryData
                Repetition (0..n)