What is the role of commentary, including commentary on standard form contracts, when it comes to interpreting contracts?

Often construction contracts are based on a standard form contract, such as the forms issued by the Joint Contracts Tribunal (JCT), the Institution of Civil Engineers (NEC), or the International Federation of Consulting Engineers (FIDIC).

When a dispute arises as to the meaning of a particular provision in a standard form contract, parties may seek to rely on guidance or commentary on the standard form (as well as other authorities) to support their arguments in relation to the interpretation of that provision. Alternatively, a party may wish to distance itself from any guidance or commentary and argue for a different interpretation of the relevant provision in the specific circumstances of the case. Where guidance or commentary on a particular provision is available, does it have a role to play before the court or tribunal interpreting the standard form contract provisions?

There is no simple set of rules to follow in respect of how contracts may be construed and interpreted. Over the years a considerable body of case