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MkII FPA was developed in the late 80’s by Charles Symons in the UK. He aimed to improve on Albrecht’s size index (IFPUG FPA) and designed the method to be compatible with ideas from structured analysis and design.
The MkII method assumes a model of software in which all requirements or ‘user functionality’ is expressed in terms of ‘Logical Transactions’, where each LT comprises an input, some processing and an output component. An LT is defined as being triggered by an event in the real world of interest to the user, or a request for information.
The size of any input and output component of an LT is taken to be proportional to the number of DETs (Data Element Types) on the component, whilst the size of the processing component is taken to be proportional to the number of entity-types which are referenced in the processing. The counts of input and output DETs and of entity-types referenced in the processing phase are then weighted to give the MkII FP size of each LT. The size of an item of software is then the sum of the MkII FP sizes of each of its LTs.
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