If an organization issues a document Rules of the Sport of X, that organization should also issue another document— Guide to the Interpretation of the Rules of X. Here’s why.
In order to be effective, a set of rules governing any activity needs to be both concise and precise; both short and clear. Every sentence should be phrased carefully and be grammatically correct. Slang and verbosity, which may cause confusion, should be rigorously avoided. Every word should be the right word, every word should count, and two words should never be used where one would do. Technical terms should be introduced explicitly, defined carefully, and used consistently. No rule should be stated twice— especially if it is worded differently in different places.
With a novel or a newspaper or a magazine article we read along, get the general gist of things, and that is all we need. We’re not used to reading documents that are written in the tight, compressed, precise way that a good rules document is written. That is why, in addition to rules documents, we need rules guides. The purpose of a rules guide is to translate the compressed language of a rules document into the kind of language that we normally use in everyday life, so that players can more easily understand the full meaning and implication of the rules.
A rules guide document is a collection of comments on the rules. One thing that a comment can do is to point out implications of a particular rule. For example, when a single word (“only if” rather than “if) has significant implications for the meaning of a rule, a comment can point that out. Sometimes the full significance of a rule can be seen only when it is placed in a wider historical or cultural context— comments can provide that wider context. In some situations there may seem to be no applicable rule, or multiple contradictory applicable rules— a rules guide can note the existence of such situations and explain how to deal with them.
A rules guide will almost certainly need to be revised more frequently than a rules document. With time, players will inevitably find new ways to be confused by the rules, and will come up with new questions about the rules. The rules (if they were well-written) won’t need to be revised, but the rules guide will need to be updated to deal with such new confusions and questions as they emerge.
Note that a rules guide is not the same thing as an umpire’s guide. A rules guide contains comments on the rules of the game. An umpire’s guide contains guidelines, advice, and instructions for umpires, telling them how to perform their roles as umpires. A petanque umpires’ guide, for instance, would help umpires in deciding when to impose penalties and which penalties to impose; how to reach a decision when teams offer conflicting stories about what happened; and so on.
Ideally we would have three separate documents— the rules, a rules guide, and an umpire’s guide. In the case of petanque what we actually have is only the FIPJP’s international rules in which umpire guidelines are intermixed with rules of the game. There is no separate FIPJP rules guide or umpire’s guide. Some national federations also issue a “rules interpretations guidelines for umpires” that contains rules guides and umpire’s guidelines.