5 modo como se distribuem e se coordenam os diversos elementos de um todo; organização, estrutura
Ex.: a economia de um conto
(Houaiss 2009)

where changes were expensive and led to substantial overruns
of the contract price many contract supervisors and
contractors agreed to offset the extra cost by reducing other
quantities or work. The justification for these cutbacks was
not adequately verified, even though they are just as important
for the economics of the contract and the quality of
results as increases are.

"são tão importantes como os aumentos relativos à economia do contrato e à qualidade dos resultados, não é devidamente controlada."

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Note added at 5 mins (2016-06-25 10:56:11 GMT)
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see Enconomics of Contracts - http://catdir.loc.gov/catdir/samples/cam033/2002019300.pdf

Seria a minha sugestão, ver:

64. Esta interpretação não infirma a ideia segundo a qual, atendendo ao imperativo da defesa dos consumidores, o juiz nacional deve, na medida do possível, privilegiar um conceito relativamente restrito do que constitui o objeto principal do contrato. A abordagem a adotar para a definição do conceito de objeto principal do contrato, prevista no artigo 4.°, n.° 2, da Diretiva 93/13, deve conduzir à exclusão das disposições que tenham caráter secundário ou residual na economia do contrato, e não das que digam respeito a uma ou várias das prestações essenciais que o caracterizam.

64. This interpretation does not invalidate the idea that, in the light of the requirement of consumer protection, the national court must, as far as possible, favour a relatively strict notion of what constitutes the main subject-matter of the contract. The approach that must be taken in defining the notion of the main subject-matter of the contract for the purposes of Article 4(2) of Directive 93/13 must result in the exclusion of provisions having a secondary or residual character in the scheme of the contract and not of those that concern one or more essential obligations characterising the contract.
http://eur-lex.europa.eu/legal-content/EN-PT/TXT/?uri=CELEX:...

Cognate with 'wirtschaftlich' (economically) in German contracts and near-equivalent to economia in ES and économie in FR: FHS Bridge's Council of Europe glossary: structure (*scheme* pace Teresa, logic) of a convention; tenor of a contract provision.

Consider; honouring a check/honoring a check according to its tenor,

Sugestão

"As long as there exists a change in the terms of our deal that would produce net benefits, there is a way of making that change that benefits both of us. Hence we would expect rational bargainers to come up with contract terms that maximize the net gain. If our objective is economic efficiency, that is both an attractive outcome and an argument for enforcing contracts as written."

see also "efficient breach", or "The economics of breach of contract"