Requirement is a Database for Tracking Share Transactions in a Fund
It is necessary to link specific investor purchases (subscriptions are in units and 
can be in purchased in fractions of a unit) with sales. 
One purchase can have many sales and one sale can comprise many purchases. 
For example, Investor A purchases shares in three lots over a 12 month period. 
Lot 1 … 220.8 shares, 
Lot 2 … 400.75 shares and 
Lot 3 … 334 shares. 
Investor A then sells 700 shares. 
There is a need to link this sale to each of the individual lots on a 'First-In First-Out' basis,
so that the remaining balance is related to Lot 3. 
One key question is 'How should Reference Data be modelled ?'
A. What are the Things Of Interest ?
A.1 Investors
A.2 Lots
A.3 Purchases
A.4 Sales
A.5 Subscriptions
A.6 Transactions.