Most standards can be categorised according to the function they need to perform. The most common is the Specification, which is a highly prescriptive standard setting out detailed absolute requirements. It is commonly used for product safety purposes or for other applications where a high degree of certainty and assurance is required by its user community.
Codes of practice recommend sound good practice as currently undertaken by competent and conscientious practitioners. They are drafted to incorporate a degree of flexibility in application, whilst offering reliable indicative benchmarks. They are commonly used in the construction and civil engineering industries.
Methods are also highly prescriptive, setting out an agreed way of measuring, testing or specifying what is reliably repeatable in different circumstances and places, wherever it needs to be applied.
A Vocabulary is a set of terms and definitions to help harmonise the use of language in a particular subject or discipline.
Guides are published to give less prescriptive advice which reflects the current thinking and practice amongst experts in a particular subject.
Other categories of standard can be employed as necessary.